1 ------------------------------------------------------------------------------
3 -- GNAT COMPILER COMPONENTS --
9 -- Copyright (C) 1992-2007, Free Software Foundation, Inc. --
11 -- GNAT is free software; you can redistribute it and/or modify it under --
12 -- terms of the GNU General Public License as published by the Free Soft- --
13 -- ware Foundation; either version 3, or (at your option) any later ver- --
14 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
15 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
16 -- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
17 -- for more details. You should have received a copy of the GNU General --
18 -- Public License distributed with GNAT; see file COPYING3. If not, go to --
19 -- http://www.gnu.org/licenses for a complete copy of the license. --
21 -- GNAT was originally developed by the GNAT team at New York University. --
22 -- Extensive contributions were provided by Ada Core Technologies Inc. --
24 ------------------------------------------------------------------------------
26 with Atree; use Atree;
27 with Checks; use Checks;
28 with Debug; use Debug;
29 with Einfo; use Einfo;
30 with Elists; use Elists;
31 with Errout; use Errout;
32 with Eval_Fat; use Eval_Fat;
33 with Exp_Util; use Exp_Util;
35 with Namet; use Namet;
36 with Nmake; use Nmake;
37 with Nlists; use Nlists;
40 with Sem_Cat; use Sem_Cat;
41 with Sem_Ch6; use Sem_Ch6;
42 with Sem_Ch8; use Sem_Ch8;
43 with Sem_Res; use Sem_Res;
44 with Sem_Util; use Sem_Util;
45 with Sem_Type; use Sem_Type;
46 with Sem_Warn; use Sem_Warn;
47 with Sinfo; use Sinfo;
48 with Snames; use Snames;
49 with Stand; use Stand;
50 with Stringt; use Stringt;
51 with Tbuild; use Tbuild;
53 package body Sem_Eval is
55 -----------------------------------------
56 -- Handling of Compile Time Evaluation --
57 -----------------------------------------
59 -- The compile time evaluation of expressions is distributed over several
60 -- Eval_xxx procedures. These procedures are called immediatedly after
61 -- a subexpression is resolved and is therefore accomplished in a bottom
62 -- up fashion. The flags are synthesized using the following approach.
64 -- Is_Static_Expression is determined by following the detailed rules
65 -- in RM 4.9(4-14). This involves testing the Is_Static_Expression
66 -- flag of the operands in many cases.
68 -- Raises_Constraint_Error is set if any of the operands have the flag
69 -- set or if an attempt to compute the value of the current expression
70 -- results in detection of a runtime constraint error.
72 -- As described in the spec, the requirement is that Is_Static_Expression
73 -- be accurately set, and in addition for nodes for which this flag is set,
74 -- Raises_Constraint_Error must also be set. Furthermore a node which has
75 -- Is_Static_Expression set, and Raises_Constraint_Error clear, then the
76 -- requirement is that the expression value must be precomputed, and the
77 -- node is either a literal, or the name of a constant entity whose value
78 -- is a static expression.
80 -- The general approach is as follows. First compute Is_Static_Expression.
81 -- If the node is not static, then the flag is left off in the node and
82 -- we are all done. Otherwise for a static node, we test if any of the
83 -- operands will raise constraint error, and if so, propagate the flag
84 -- Raises_Constraint_Error to the result node and we are done (since the
85 -- error was already posted at a lower level).
87 -- For the case of a static node whose operands do not raise constraint
88 -- error, we attempt to evaluate the node. If this evaluation succeeds,
89 -- then the node is replaced by the result of this computation. If the
90 -- evaluation raises constraint error, then we rewrite the node with
91 -- Apply_Compile_Time_Constraint_Error to raise the exception and also
92 -- to post appropriate error messages.
98 type Bits is array (Nat range <>) of Boolean;
99 -- Used to convert unsigned (modular) values for folding logical ops
101 -- The following definitions are used to maintain a cache of nodes that
102 -- have compile time known values. The cache is maintained only for
103 -- discrete types (the most common case), and is populated by calls to
104 -- Compile_Time_Known_Value and Expr_Value, but only used by Expr_Value
105 -- since it is possible for the status to change (in particular it is
106 -- possible for a node to get replaced by a constraint error node).
108 CV_Bits : constant := 5;
109 -- Number of low order bits of Node_Id value used to reference entries
110 -- in the cache table.
112 CV_Cache_Size : constant Nat := 2 ** CV_Bits;
113 -- Size of cache for compile time values
115 subtype CV_Range is Nat range 0 .. CV_Cache_Size;
117 type CV_Entry is record
122 type CV_Cache_Array is array (CV_Range) of CV_Entry;
124 CV_Cache : CV_Cache_Array := (others => (Node_High_Bound, Uint_0));
125 -- This is the actual cache, with entries consisting of node/value pairs,
126 -- and the impossible value Node_High_Bound used for unset entries.
128 -----------------------
129 -- Local Subprograms --
130 -----------------------
132 function From_Bits (B : Bits; T : Entity_Id) return Uint;
133 -- Converts a bit string of length B'Length to a Uint value to be used
134 -- for a target of type T, which is a modular type. This procedure
135 -- includes the necessary reduction by the modulus in the case of a
136 -- non-binary modulus (for a binary modulus, the bit string is the
137 -- right length any way so all is well).
139 function Get_String_Val (N : Node_Id) return Node_Id;
140 -- Given a tree node for a folded string or character value, returns
141 -- the corresponding string literal or character literal (one of the
142 -- two must be available, or the operand would not have been marked
143 -- as foldable in the earlier analysis of the operation).
145 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean;
146 -- Bits represents the number of bits in an integer value to be computed
147 -- (but the value has not been computed yet). If this value in Bits is
148 -- reasonable, a result of True is returned, with the implication that
149 -- the caller should go ahead and complete the calculation. If the value
150 -- in Bits is unreasonably large, then an error is posted on node N, and
151 -- False is returned (and the caller skips the proposed calculation).
153 procedure Out_Of_Range (N : Node_Id);
154 -- This procedure is called if it is determined that node N, which
155 -- appears in a non-static context, is a compile time known value
156 -- which is outside its range, i.e. the range of Etype. This is used
157 -- in contexts where this is an illegality if N is static, and should
158 -- generate a warning otherwise.
160 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id);
161 -- N and Exp are nodes representing an expression, Exp is known
162 -- to raise CE. N is rewritten in term of Exp in the optimal way.
164 function String_Type_Len (Stype : Entity_Id) return Uint;
165 -- Given a string type, determines the length of the index type, or,
166 -- if this index type is non-static, the length of the base type of
167 -- this index type. Note that if the string type is itself static,
168 -- then the index type is static, so the second case applies only
169 -- if the string type passed is non-static.
171 function Test (Cond : Boolean) return Uint;
172 pragma Inline (Test);
173 -- This function simply returns the appropriate Boolean'Pos value
174 -- corresponding to the value of Cond as a universal integer. It is
175 -- used for producing the result of the static evaluation of the
178 procedure Test_Expression_Is_Foldable
183 -- Tests to see if expression N whose single operand is Op1 is foldable,
184 -- i.e. the operand value is known at compile time. If the operation is
185 -- foldable, then Fold is True on return, and Stat indicates whether
186 -- the result is static (i.e. both operands were static). Note that it
187 -- is quite possible for Fold to be True, and Stat to be False, since
188 -- there are cases in which we know the value of an operand even though
189 -- it is not technically static (e.g. the static lower bound of a range
190 -- whose upper bound is non-static).
192 -- If Stat is set False on return, then Expression_Is_Foldable makes a
193 -- call to Check_Non_Static_Context on the operand. If Fold is False on
194 -- return, then all processing is complete, and the caller should
195 -- return, since there is nothing else to do.
197 procedure Test_Expression_Is_Foldable
203 -- Same processing, except applies to an expression N with two operands
206 procedure To_Bits (U : Uint; B : out Bits);
207 -- Converts a Uint value to a bit string of length B'Length
209 ------------------------------
210 -- Check_Non_Static_Context --
211 ------------------------------
213 procedure Check_Non_Static_Context (N : Node_Id) is
214 T : constant Entity_Id := Etype (N);
215 Checks_On : constant Boolean :=
216 not Index_Checks_Suppressed (T)
217 and not Range_Checks_Suppressed (T);
220 -- Ignore cases of non-scalar types or error types
222 if T = Any_Type or else not Is_Scalar_Type (T) then
226 -- At this stage we have a scalar type. If we have an expression
227 -- that raises CE, then we already issued a warning or error msg
228 -- so there is nothing more to be done in this routine.
230 if Raises_Constraint_Error (N) then
234 -- Now we have a scalar type which is not marked as raising a
235 -- constraint error exception. The main purpose of this routine
236 -- is to deal with static expressions appearing in a non-static
237 -- context. That means that if we do not have a static expression
238 -- then there is not much to do. The one case that we deal with
239 -- here is that if we have a floating-point value that is out of
240 -- range, then we post a warning that an infinity will result.
242 if not Is_Static_Expression (N) then
243 if Is_Floating_Point_Type (T)
244 and then Is_Out_Of_Range (N, Base_Type (T))
247 ("?float value out of range, infinity will be generated", N);
253 -- Here we have the case of outer level static expression of
254 -- scalar type, where the processing of this procedure is needed.
256 -- For real types, this is where we convert the value to a machine
257 -- number (see RM 4.9(38)). Also see ACVC test C490001. We should
258 -- only need to do this if the parent is a constant declaration,
259 -- since in other cases, gigi should do the necessary conversion
260 -- correctly, but experimentation shows that this is not the case
261 -- on all machines, in particular if we do not convert all literals
262 -- to machine values in non-static contexts, then ACVC test C490001
263 -- fails on Sparc/Solaris and SGI/Irix.
265 if Nkind (N) = N_Real_Literal
266 and then not Is_Machine_Number (N)
267 and then not Is_Generic_Type (Etype (N))
268 and then Etype (N) /= Universal_Real
270 -- Check that value is in bounds before converting to machine
271 -- number, so as not to lose case where value overflows in the
272 -- least significant bit or less. See B490001.
274 if Is_Out_Of_Range (N, Base_Type (T)) then
279 -- Note: we have to copy the node, to avoid problems with conformance
280 -- of very similar numbers (see ACVC tests B4A010C and B63103A).
282 Rewrite (N, New_Copy (N));
284 if not Is_Floating_Point_Type (T) then
286 (N, Corresponding_Integer_Value (N) * Small_Value (T));
288 elsif not UR_Is_Zero (Realval (N)) then
290 -- Note: even though RM 4.9(38) specifies biased rounding,
291 -- this has been modified by AI-100 in order to prevent
292 -- confusing differences in rounding between static and
293 -- non-static expressions. AI-100 specifies that the effect
294 -- of such rounding is implementation dependent, and in GNAT
295 -- we round to nearest even to match the run-time behavior.
298 (N, Machine (Base_Type (T), Realval (N), Round_Even, N));
301 Set_Is_Machine_Number (N);
304 -- Check for out of range universal integer. This is a non-static
305 -- context, so the integer value must be in range of the runtime
306 -- representation of universal integers.
308 -- We do this only within an expression, because that is the only
309 -- case in which non-static universal integer values can occur, and
310 -- furthermore, Check_Non_Static_Context is currently (incorrectly???)
311 -- called in contexts like the expression of a number declaration where
312 -- we certainly want to allow out of range values.
314 if Etype (N) = Universal_Integer
315 and then Nkind (N) = N_Integer_Literal
316 and then Nkind (Parent (N)) in N_Subexpr
318 (Intval (N) < Expr_Value (Type_Low_Bound (Universal_Integer))
320 Intval (N) > Expr_Value (Type_High_Bound (Universal_Integer)))
322 Apply_Compile_Time_Constraint_Error
323 (N, "non-static universal integer value out of range?",
324 CE_Range_Check_Failed);
326 -- Check out of range of base type
328 elsif Is_Out_Of_Range (N, Base_Type (T)) then
331 -- Give warning if outside subtype (where one or both of the
332 -- bounds of the subtype is static). This warning is omitted
333 -- if the expression appears in a range that could be null
334 -- (warnings are handled elsewhere for this case).
336 elsif T /= Base_Type (T)
337 and then Nkind (Parent (N)) /= N_Range
339 if Is_In_Range (N, T) then
342 elsif Is_Out_Of_Range (N, T) then
343 Apply_Compile_Time_Constraint_Error
344 (N, "value not in range of}?", CE_Range_Check_Failed);
347 Enable_Range_Check (N);
350 Set_Do_Range_Check (N, False);
353 end Check_Non_Static_Context;
355 ---------------------------------
356 -- Check_String_Literal_Length --
357 ---------------------------------
359 procedure Check_String_Literal_Length (N : Node_Id; Ttype : Entity_Id) is
361 if not Raises_Constraint_Error (N)
362 and then Is_Constrained (Ttype)
365 UI_From_Int (String_Length (Strval (N))) /= String_Type_Len (Ttype)
367 Apply_Compile_Time_Constraint_Error
368 (N, "string length wrong for}?",
369 CE_Length_Check_Failed,
374 end Check_String_Literal_Length;
376 --------------------------
377 -- Compile_Time_Compare --
378 --------------------------
380 function Compile_Time_Compare
382 Rec : Boolean := False) return Compare_Result
384 Ltyp : constant Entity_Id := Etype (L);
385 Rtyp : constant Entity_Id := Etype (R);
387 procedure Compare_Decompose
391 -- This procedure decomposes the node N into an expression node
392 -- and a signed offset, so that the value of N is equal to the
393 -- value of R plus the value V (which may be negative). If no
394 -- such decomposition is possible, then on return R is a copy
395 -- of N, and V is set to zero.
397 function Compare_Fixup (N : Node_Id) return Node_Id;
398 -- This function deals with replacing 'Last and 'First references
399 -- with their corresponding type bounds, which we then can compare.
400 -- The argument is the original node, the result is the identity,
401 -- unless we have a 'Last/'First reference in which case the value
402 -- returned is the appropriate type bound.
404 function Is_Same_Value (L, R : Node_Id) return Boolean;
405 -- Returns True iff L and R represent expressions that definitely
406 -- have identical (but not necessarily compile time known) values
407 -- Indeed the caller is expected to have already dealt with the
408 -- cases of compile time known values, so these are not tested here.
410 -----------------------
411 -- Compare_Decompose --
412 -----------------------
414 procedure Compare_Decompose
420 if Nkind (N) = N_Op_Add
421 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
424 V := Intval (Right_Opnd (N));
427 elsif Nkind (N) = N_Op_Subtract
428 and then Nkind (Right_Opnd (N)) = N_Integer_Literal
431 V := UI_Negate (Intval (Right_Opnd (N)));
434 elsif Nkind (N) = N_Attribute_Reference then
436 if Attribute_Name (N) = Name_Succ then
437 R := First (Expressions (N));
441 elsif Attribute_Name (N) = Name_Pred then
442 R := First (Expressions (N));
450 end Compare_Decompose;
456 function Compare_Fixup (N : Node_Id) return Node_Id is
462 if Nkind (N) = N_Attribute_Reference
463 and then (Attribute_Name (N) = Name_First
465 Attribute_Name (N) = Name_Last)
467 Xtyp := Etype (Prefix (N));
469 -- If we have no type, then just abandon the attempt to do
470 -- a fixup, this is probably the result of some other error.
476 -- Dereference an access type
478 if Is_Access_Type (Xtyp) then
479 Xtyp := Designated_Type (Xtyp);
482 -- If we don't have an array type at this stage, something
483 -- is peculiar, e.g. another error, and we abandon the attempt
486 if not Is_Array_Type (Xtyp) then
490 -- Ignore unconstrained array, since bounds are not meaningful
492 if not Is_Constrained (Xtyp) then
496 if Ekind (Xtyp) = E_String_Literal_Subtype then
497 if Attribute_Name (N) = Name_First then
498 return String_Literal_Low_Bound (Xtyp);
500 else -- Attribute_Name (N) = Name_Last
501 return Make_Integer_Literal (Sloc (N),
502 Intval => Intval (String_Literal_Low_Bound (Xtyp))
503 + String_Literal_Length (Xtyp));
507 -- Find correct index type
509 Indx := First_Index (Xtyp);
511 if Present (Expressions (N)) then
512 Subs := UI_To_Int (Expr_Value (First (Expressions (N))));
514 for J in 2 .. Subs loop
515 Indx := Next_Index (Indx);
519 Xtyp := Etype (Indx);
521 if Attribute_Name (N) = Name_First then
522 return Type_Low_Bound (Xtyp);
524 else -- Attribute_Name (N) = Name_Last
525 return Type_High_Bound (Xtyp);
536 function Is_Same_Value (L, R : Node_Id) return Boolean is
537 Lf : constant Node_Id := Compare_Fixup (L);
538 Rf : constant Node_Id := Compare_Fixup (R);
540 function Is_Same_Subscript (L, R : List_Id) return Boolean;
541 -- L, R are the Expressions values from two attribute nodes
542 -- for First or Last attributes. Either may be set to No_List
543 -- if no expressions are present (indicating subscript 1).
544 -- The result is True if both expressions represent the same
545 -- subscript (note that one case is where one subscript is
546 -- missing and the other is explicitly set to 1).
548 -----------------------
549 -- Is_Same_Subscript --
550 -----------------------
552 function Is_Same_Subscript (L, R : List_Id) return Boolean is
558 return Expr_Value (First (R)) = Uint_1;
563 return Expr_Value (First (L)) = Uint_1;
565 return Expr_Value (First (L)) = Expr_Value (First (R));
568 end Is_Same_Subscript;
570 -- Start of processing for Is_Same_Value
573 -- Values are the same if they are the same identifier and the
574 -- identifier refers to a constant object (E_Constant). This
575 -- does not however apply to Float types, since we may have two
576 -- NaN values and they should never compare equal.
578 if Nkind (Lf) = N_Identifier and then Nkind (Rf) = N_Identifier
579 and then Entity (Lf) = Entity (Rf)
580 and then not Is_Floating_Point_Type (Etype (L))
581 and then (Ekind (Entity (Lf)) = E_Constant or else
582 Ekind (Entity (Lf)) = E_In_Parameter or else
583 Ekind (Entity (Lf)) = E_Loop_Parameter)
587 -- Or if they are compile time known and identical
589 elsif Compile_Time_Known_Value (Lf)
591 Compile_Time_Known_Value (Rf)
592 and then Expr_Value (Lf) = Expr_Value (Rf)
596 -- Or if they are both 'First or 'Last values applying to the
597 -- same entity (first and last don't change even if value does)
599 elsif Nkind (Lf) = N_Attribute_Reference
601 Nkind (Rf) = N_Attribute_Reference
602 and then Attribute_Name (Lf) = Attribute_Name (Rf)
603 and then (Attribute_Name (Lf) = Name_First
605 Attribute_Name (Lf) = Name_Last)
606 and then Is_Entity_Name (Prefix (Lf))
607 and then Is_Entity_Name (Prefix (Rf))
608 and then Entity (Prefix (Lf)) = Entity (Prefix (Rf))
609 and then Is_Same_Subscript (Expressions (Lf), Expressions (Rf))
613 -- All other cases, we can't tell
620 -- Start of processing for Compile_Time_Compare
623 -- If either operand could raise constraint error, then we cannot
624 -- know the result at compile time (since CE may be raised!)
626 if not (Cannot_Raise_Constraint_Error (L)
628 Cannot_Raise_Constraint_Error (R))
633 -- Identical operands are most certainly equal
638 -- If expressions have no types, then do not attempt to determine
639 -- if they are the same, since something funny is going on. One
640 -- case in which this happens is during generic template analysis,
641 -- when bounds are not fully analyzed.
643 elsif No (Ltyp) or else No (Rtyp) then
646 -- We only attempt compile time analysis for scalar values, and
647 -- not for packed arrays represented as modular types, where the
648 -- semantics of comparison is quite different.
650 elsif not Is_Scalar_Type (Ltyp)
651 or else Is_Packed_Array_Type (Ltyp)
655 -- Case where comparison involves two compile time known values
657 elsif Compile_Time_Known_Value (L)
658 and then Compile_Time_Known_Value (R)
660 -- For the floating-point case, we have to be a little careful, since
661 -- at compile time we are dealing with universal exact values, but at
662 -- runtime, these will be in non-exact target form. That's why the
663 -- returned results are LE and GE below instead of LT and GT.
665 if Is_Floating_Point_Type (Ltyp)
667 Is_Floating_Point_Type (Rtyp)
670 Lo : constant Ureal := Expr_Value_R (L);
671 Hi : constant Ureal := Expr_Value_R (R);
683 -- For the integer case we know exactly (note that this includes the
684 -- fixed-point case, where we know the run time integer values now)
688 Lo : constant Uint := Expr_Value (L);
689 Hi : constant Uint := Expr_Value (R);
702 -- Cases where at least one operand is not known at compile time
705 -- Remaining checks apply only for non-generic discrete types
707 if not Is_Discrete_Type (Ltyp)
708 or else not Is_Discrete_Type (Rtyp)
709 or else Is_Generic_Type (Ltyp)
710 or else Is_Generic_Type (Rtyp)
715 -- Here is where we check for comparisons against maximum bounds of
716 -- types, where we know that no value can be outside the bounds of
717 -- the subtype. Note that this routine is allowed to assume that all
718 -- expressions are within their subtype bounds. Callers wishing to
719 -- deal with possibly invalid values must in any case take special
720 -- steps (e.g. conversions to larger types) to avoid this kind of
721 -- optimization, which is always considered to be valid. We do not
722 -- attempt this optimization with generic types, since the type
723 -- bounds may not be meaningful in this case.
725 -- We are in danger of an infinite recursion here. It does not seem
726 -- useful to go more than one level deep, so the parameter Rec is
727 -- used to protect ourselves against this infinite recursion.
731 -- See if we can get a decisive check against one operand and
732 -- a bound of the other operand (four possible tests here).
734 case Compile_Time_Compare (L, Type_Low_Bound (Rtyp), True) is
735 when LT => return LT;
736 when LE => return LE;
737 when EQ => return LE;
741 case Compile_Time_Compare (L, Type_High_Bound (Rtyp), True) is
742 when GT => return GT;
743 when GE => return GE;
744 when EQ => return GE;
748 case Compile_Time_Compare (Type_Low_Bound (Ltyp), R, True) is
749 when GT => return GT;
750 when GE => return GE;
751 when EQ => return GE;
755 case Compile_Time_Compare (Type_High_Bound (Ltyp), R, True) is
756 when LT => return LT;
757 when LE => return LE;
758 when EQ => return LE;
763 -- Next attempt is to decompose the expressions to extract
764 -- a constant offset resulting from the use of any of the forms:
771 -- Then we see if the two expressions are the same value, and if so
772 -- the result is obtained by comparing the offsets.
781 Compare_Decompose (L, Lnode, Loffs);
782 Compare_Decompose (R, Rnode, Roffs);
784 if Is_Same_Value (Lnode, Rnode) then
785 if Loffs = Roffs then
788 elsif Loffs < Roffs then
797 -- Next attempt is to see if we have an entity compared with a
798 -- compile time known value, where there is a current value
799 -- conditional for the entity which can tell us the result.
803 -- Entity variable (left operand)
806 -- Value (right operand)
809 -- If False, we have reversed the operands
812 -- Comparison operator kind from Get_Current_Value_Condition call
815 -- Value from Get_Current_Value_Condition call
820 Result : Compare_Result;
821 -- Known result before inversion
824 if Is_Entity_Name (L)
825 and then Compile_Time_Known_Value (R)
828 Val := Expr_Value (R);
831 elsif Is_Entity_Name (R)
832 and then Compile_Time_Known_Value (L)
835 Val := Expr_Value (L);
838 -- That was the last chance at finding a compile time result
844 Get_Current_Value_Condition (Var, Op, Opn);
846 -- That was the last chance, so if we got nothing return
852 Opv := Expr_Value (Opn);
854 -- We got a comparison, so we might have something interesting
856 -- Convert LE to LT and GE to GT, just so we have fewer cases
861 elsif Op = N_Op_Ge then
866 -- Deal with equality case
877 -- Deal with inequality case
879 elsif Op = N_Op_Ne then
886 -- Deal with greater than case
888 elsif Op = N_Op_Gt then
891 elsif Opv = Val - 1 then
897 -- Deal with less than case
899 else pragma Assert (Op = N_Op_Lt);
902 elsif Opv = Val + 1 then
909 -- Deal with inverting result
913 when GT => return LT;
914 when GE => return LE;
915 when LT => return GT;
916 when LE => return GE;
917 when others => return Result;
924 end Compile_Time_Compare;
926 -------------------------------
927 -- Compile_Time_Known_Bounds --
928 -------------------------------
930 function Compile_Time_Known_Bounds (T : Entity_Id) return Boolean is
935 if not Is_Array_Type (T) then
939 Indx := First_Index (T);
940 while Present (Indx) loop
941 Typ := Underlying_Type (Etype (Indx));
942 if not Compile_Time_Known_Value (Type_Low_Bound (Typ)) then
944 elsif not Compile_Time_Known_Value (Type_High_Bound (Typ)) then
952 end Compile_Time_Known_Bounds;
954 ------------------------------
955 -- Compile_Time_Known_Value --
956 ------------------------------
958 function Compile_Time_Known_Value (Op : Node_Id) return Boolean is
959 K : constant Node_Kind := Nkind (Op);
960 CV_Ent : CV_Entry renames CV_Cache (Nat (Op) mod CV_Cache_Size);
963 -- Never known at compile time if bad type or raises constraint error
964 -- or empty (latter case occurs only as a result of a previous error)
968 or else Etype (Op) = Any_Type
969 or else Raises_Constraint_Error (Op)
974 -- If this is not a static expression and we are in configurable run
975 -- time mode, then we consider it not known at compile time. This
976 -- avoids anomalies where whether something is permitted with a given
977 -- configurable run-time library depends on how good the compiler is
978 -- at optimizing and knowing that things are constant when they
981 if Configurable_Run_Time_Mode and then not Is_Static_Expression (Op) then
985 -- If we have an entity name, then see if it is the name of a constant
986 -- and if so, test the corresponding constant value, or the name of
987 -- an enumeration literal, which is always a constant.
989 if Present (Etype (Op)) and then Is_Entity_Name (Op) then
991 E : constant Entity_Id := Entity (Op);
995 -- Never known at compile time if it is a packed array value.
996 -- We might want to try to evaluate these at compile time one
997 -- day, but we do not make that attempt now.
999 if Is_Packed_Array_Type (Etype (Op)) then
1003 if Ekind (E) = E_Enumeration_Literal then
1006 elsif Ekind (E) = E_Constant then
1007 V := Constant_Value (E);
1008 return Present (V) and then Compile_Time_Known_Value (V);
1012 -- We have a value, see if it is compile time known
1015 -- Integer literals are worth storing in the cache
1017 if K = N_Integer_Literal then
1019 CV_Ent.V := Intval (Op);
1022 -- Other literals and NULL are known at compile time
1025 K = N_Character_Literal
1029 K = N_String_Literal
1035 -- Any reference to Null_Parameter is known at compile time. No
1036 -- other attribute references (that have not already been folded)
1037 -- are known at compile time.
1039 elsif K = N_Attribute_Reference then
1040 return Attribute_Name (Op) = Name_Null_Parameter;
1044 -- If we fall through, not known at compile time
1048 -- If we get an exception while trying to do this test, then some error
1049 -- has occurred, and we simply say that the value is not known after all
1054 end Compile_Time_Known_Value;
1056 --------------------------------------
1057 -- Compile_Time_Known_Value_Or_Aggr --
1058 --------------------------------------
1060 function Compile_Time_Known_Value_Or_Aggr (Op : Node_Id) return Boolean is
1062 -- If we have an entity name, then see if it is the name of a constant
1063 -- and if so, test the corresponding constant value, or the name of
1064 -- an enumeration literal, which is always a constant.
1066 if Is_Entity_Name (Op) then
1068 E : constant Entity_Id := Entity (Op);
1072 if Ekind (E) = E_Enumeration_Literal then
1075 elsif Ekind (E) /= E_Constant then
1079 V := Constant_Value (E);
1081 and then Compile_Time_Known_Value_Or_Aggr (V);
1085 -- We have a value, see if it is compile time known
1088 if Compile_Time_Known_Value (Op) then
1091 elsif Nkind (Op) = N_Aggregate then
1093 if Present (Expressions (Op)) then
1098 Expr := First (Expressions (Op));
1099 while Present (Expr) loop
1100 if not Compile_Time_Known_Value_Or_Aggr (Expr) then
1109 if Present (Component_Associations (Op)) then
1114 Cass := First (Component_Associations (Op));
1115 while Present (Cass) loop
1117 Compile_Time_Known_Value_Or_Aggr (Expression (Cass))
1129 -- All other types of values are not known at compile time
1136 end Compile_Time_Known_Value_Or_Aggr;
1142 -- This is only called for actuals of functions that are not predefined
1143 -- operators (which have already been rewritten as operators at this
1144 -- stage), so the call can never be folded, and all that needs doing for
1145 -- the actual is to do the check for a non-static context.
1147 procedure Eval_Actual (N : Node_Id) is
1149 Check_Non_Static_Context (N);
1152 --------------------
1153 -- Eval_Allocator --
1154 --------------------
1156 -- Allocators are never static, so all we have to do is to do the
1157 -- check for a non-static context if an expression is present.
1159 procedure Eval_Allocator (N : Node_Id) is
1160 Expr : constant Node_Id := Expression (N);
1163 if Nkind (Expr) = N_Qualified_Expression then
1164 Check_Non_Static_Context (Expression (Expr));
1168 ------------------------
1169 -- Eval_Arithmetic_Op --
1170 ------------------------
1172 -- Arithmetic operations are static functions, so the result is static
1173 -- if both operands are static (RM 4.9(7), 4.9(20)).
1175 procedure Eval_Arithmetic_Op (N : Node_Id) is
1176 Left : constant Node_Id := Left_Opnd (N);
1177 Right : constant Node_Id := Right_Opnd (N);
1178 Ltype : constant Entity_Id := Etype (Left);
1179 Rtype : constant Entity_Id := Etype (Right);
1184 -- If not foldable we are done
1186 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1192 -- Fold for cases where both operands are of integer type
1194 if Is_Integer_Type (Ltype) and then Is_Integer_Type (Rtype) then
1196 Left_Int : constant Uint := Expr_Value (Left);
1197 Right_Int : constant Uint := Expr_Value (Right);
1204 Result := Left_Int + Right_Int;
1206 when N_Op_Subtract =>
1207 Result := Left_Int - Right_Int;
1209 when N_Op_Multiply =>
1212 (Num_Bits (Left_Int) + Num_Bits (Right_Int)))
1214 Result := Left_Int * Right_Int;
1221 -- The exception Constraint_Error is raised by integer
1222 -- division, rem and mod if the right operand is zero.
1224 if Right_Int = 0 then
1225 Apply_Compile_Time_Constraint_Error
1226 (N, "division by zero",
1232 Result := Left_Int / Right_Int;
1237 -- The exception Constraint_Error is raised by integer
1238 -- division, rem and mod if the right operand is zero.
1240 if Right_Int = 0 then
1241 Apply_Compile_Time_Constraint_Error
1242 (N, "mod with zero divisor",
1247 Result := Left_Int mod Right_Int;
1252 -- The exception Constraint_Error is raised by integer
1253 -- division, rem and mod if the right operand is zero.
1255 if Right_Int = 0 then
1256 Apply_Compile_Time_Constraint_Error
1257 (N, "rem with zero divisor",
1263 Result := Left_Int rem Right_Int;
1267 raise Program_Error;
1270 -- Adjust the result by the modulus if the type is a modular type
1272 if Is_Modular_Integer_Type (Ltype) then
1273 Result := Result mod Modulus (Ltype);
1275 -- For a signed integer type, check non-static overflow
1277 elsif (not Stat) and then Is_Signed_Integer_Type (Ltype) then
1279 BT : constant Entity_Id := Base_Type (Ltype);
1280 Lo : constant Uint := Expr_Value (Type_Low_Bound (BT));
1281 Hi : constant Uint := Expr_Value (Type_High_Bound (BT));
1283 if Result < Lo or else Result > Hi then
1284 Apply_Compile_Time_Constraint_Error
1285 (N, "value not in range of }?",
1286 CE_Overflow_Check_Failed,
1293 -- If we get here we can fold the result
1295 Fold_Uint (N, Result, Stat);
1298 -- Cases where at least one operand is a real. We handle the cases
1299 -- of both reals, or mixed/real integer cases (the latter happen
1300 -- only for divide and multiply, and the result is always real).
1302 elsif Is_Real_Type (Ltype) or else Is_Real_Type (Rtype) then
1309 if Is_Real_Type (Ltype) then
1310 Left_Real := Expr_Value_R (Left);
1312 Left_Real := UR_From_Uint (Expr_Value (Left));
1315 if Is_Real_Type (Rtype) then
1316 Right_Real := Expr_Value_R (Right);
1318 Right_Real := UR_From_Uint (Expr_Value (Right));
1321 if Nkind (N) = N_Op_Add then
1322 Result := Left_Real + Right_Real;
1324 elsif Nkind (N) = N_Op_Subtract then
1325 Result := Left_Real - Right_Real;
1327 elsif Nkind (N) = N_Op_Multiply then
1328 Result := Left_Real * Right_Real;
1330 else pragma Assert (Nkind (N) = N_Op_Divide);
1331 if UR_Is_Zero (Right_Real) then
1332 Apply_Compile_Time_Constraint_Error
1333 (N, "division by zero", CE_Divide_By_Zero);
1337 Result := Left_Real / Right_Real;
1340 Fold_Ureal (N, Result, Stat);
1343 end Eval_Arithmetic_Op;
1345 ----------------------------
1346 -- Eval_Character_Literal --
1347 ----------------------------
1349 -- Nothing to be done!
1351 procedure Eval_Character_Literal (N : Node_Id) is
1352 pragma Warnings (Off, N);
1355 end Eval_Character_Literal;
1361 -- Static function calls are either calls to predefined operators
1362 -- with static arguments, or calls to functions that rename a literal.
1363 -- Only the latter case is handled here, predefined operators are
1364 -- constant-folded elsewhere.
1366 -- If the function is itself inherited (see 7423-001) the literal of
1367 -- the parent type must be explicitly converted to the return type
1370 procedure Eval_Call (N : Node_Id) is
1371 Loc : constant Source_Ptr := Sloc (N);
1372 Typ : constant Entity_Id := Etype (N);
1376 if Nkind (N) = N_Function_Call
1377 and then No (Parameter_Associations (N))
1378 and then Is_Entity_Name (Name (N))
1379 and then Present (Alias (Entity (Name (N))))
1380 and then Is_Enumeration_Type (Base_Type (Typ))
1382 Lit := Alias (Entity (Name (N)));
1383 while Present (Alias (Lit)) loop
1387 if Ekind (Lit) = E_Enumeration_Literal then
1388 if Base_Type (Etype (Lit)) /= Base_Type (Typ) then
1390 (N, Convert_To (Typ, New_Occurrence_Of (Lit, Loc)));
1392 Rewrite (N, New_Occurrence_Of (Lit, Loc));
1400 ------------------------
1401 -- Eval_Concatenation --
1402 ------------------------
1404 -- Concatenation is a static function, so the result is static if
1405 -- both operands are static (RM 4.9(7), 4.9(21)).
1407 procedure Eval_Concatenation (N : Node_Id) is
1408 Left : constant Node_Id := Left_Opnd (N);
1409 Right : constant Node_Id := Right_Opnd (N);
1410 C_Typ : constant Entity_Id := Root_Type (Component_Type (Etype (N)));
1415 -- Concatenation is never static in Ada 83, so if Ada 83
1416 -- check operand non-static context
1418 if Ada_Version = Ada_83
1419 and then Comes_From_Source (N)
1421 Check_Non_Static_Context (Left);
1422 Check_Non_Static_Context (Right);
1426 -- If not foldable we are done. In principle concatenation that yields
1427 -- any string type is static (i.e. an array type of character types).
1428 -- However, character types can include enumeration literals, and
1429 -- concatenation in that case cannot be described by a literal, so we
1430 -- only consider the operation static if the result is an array of
1431 -- (a descendant of) a predefined character type.
1433 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1435 if (C_Typ = Standard_Character
1436 or else C_Typ = Standard_Wide_Character
1437 or else C_Typ = Standard_Wide_Wide_Character)
1442 Set_Is_Static_Expression (N, False);
1446 -- Compile time string concatenation
1448 -- ??? Note that operands that are aggregates can be marked as
1449 -- static, so we should attempt at a later stage to fold
1450 -- concatenations with such aggregates.
1453 Left_Str : constant Node_Id := Get_String_Val (Left);
1455 Right_Str : constant Node_Id := Get_String_Val (Right);
1456 Folded_Val : String_Id;
1459 -- Establish new string literal, and store left operand. We make
1460 -- sure to use the special Start_String that takes an operand if
1461 -- the left operand is a string literal. Since this is optimized
1462 -- in the case where that is the most recently created string
1463 -- literal, we ensure efficient time/space behavior for the
1464 -- case of a concatenation of a series of string literals.
1466 if Nkind (Left_Str) = N_String_Literal then
1467 Left_Len := String_Length (Strval (Left_Str));
1469 -- If the left operand is the empty string, and the right operand
1470 -- is a string literal (the case of "" & "..."), the result is the
1471 -- value of the right operand. This optimization is important when
1472 -- Is_Folded_In_Parser, to avoid copying an enormous right
1475 if Left_Len = 0 and then Nkind (Right_Str) = N_String_Literal then
1476 Folded_Val := Strval (Right_Str);
1478 Start_String (Strval (Left_Str));
1483 Store_String_Char (UI_To_CC (Char_Literal_Value (Left_Str)));
1487 -- Now append the characters of the right operand, unless we
1488 -- optimized the "" & "..." case above.
1490 if Nkind (Right_Str) = N_String_Literal then
1491 if Left_Len /= 0 then
1492 Store_String_Chars (Strval (Right_Str));
1493 Folded_Val := End_String;
1496 Store_String_Char (UI_To_CC (Char_Literal_Value (Right_Str)));
1497 Folded_Val := End_String;
1500 Set_Is_Static_Expression (N, Stat);
1504 -- If left operand is the empty string, the result is the
1505 -- right operand, including its bounds if anomalous.
1508 and then Is_Array_Type (Etype (Right))
1509 and then Etype (Right) /= Any_String
1511 Set_Etype (N, Etype (Right));
1514 Fold_Str (N, Folded_Val, Static => True);
1517 end Eval_Concatenation;
1519 ---------------------------------
1520 -- Eval_Conditional_Expression --
1521 ---------------------------------
1523 -- This GNAT internal construct can never be statically folded, so the
1524 -- only required processing is to do the check for non-static context
1525 -- for the two expression operands.
1527 procedure Eval_Conditional_Expression (N : Node_Id) is
1528 Condition : constant Node_Id := First (Expressions (N));
1529 Then_Expr : constant Node_Id := Next (Condition);
1530 Else_Expr : constant Node_Id := Next (Then_Expr);
1533 Check_Non_Static_Context (Then_Expr);
1534 Check_Non_Static_Context (Else_Expr);
1535 end Eval_Conditional_Expression;
1537 ----------------------
1538 -- Eval_Entity_Name --
1539 ----------------------
1541 -- This procedure is used for identifiers and expanded names other than
1542 -- named numbers (see Eval_Named_Integer, Eval_Named_Real. These are
1543 -- static if they denote a static constant (RM 4.9(6)) or if the name
1544 -- denotes an enumeration literal (RM 4.9(22)).
1546 procedure Eval_Entity_Name (N : Node_Id) is
1547 Def_Id : constant Entity_Id := Entity (N);
1551 -- Enumeration literals are always considered to be constants
1552 -- and cannot raise constraint error (RM 4.9(22)).
1554 if Ekind (Def_Id) = E_Enumeration_Literal then
1555 Set_Is_Static_Expression (N);
1558 -- A name is static if it denotes a static constant (RM 4.9(5)), and
1559 -- we also copy Raise_Constraint_Error. Notice that even if non-static,
1560 -- it does not violate 10.2.1(8) here, since this is not a variable.
1562 elsif Ekind (Def_Id) = E_Constant then
1564 -- Deferred constants must always be treated as nonstatic
1565 -- outside the scope of their full view.
1567 if Present (Full_View (Def_Id))
1568 and then not In_Open_Scopes (Scope (Def_Id))
1572 Val := Constant_Value (Def_Id);
1575 if Present (Val) then
1576 Set_Is_Static_Expression
1577 (N, Is_Static_Expression (Val)
1578 and then Is_Static_Subtype (Etype (Def_Id)));
1579 Set_Raises_Constraint_Error (N, Raises_Constraint_Error (Val));
1581 if not Is_Static_Expression (N)
1582 and then not Is_Generic_Type (Etype (N))
1584 Validate_Static_Object_Name (N);
1591 -- Fall through if the name is not static
1593 Validate_Static_Object_Name (N);
1594 end Eval_Entity_Name;
1596 ----------------------------
1597 -- Eval_Indexed_Component --
1598 ----------------------------
1600 -- Indexed components are never static, so we need to perform the check
1601 -- for non-static context on the index values. Then, we check if the
1602 -- value can be obtained at compile time, even though it is non-static.
1604 procedure Eval_Indexed_Component (N : Node_Id) is
1608 -- Check for non-static context on index values
1610 Expr := First (Expressions (N));
1611 while Present (Expr) loop
1612 Check_Non_Static_Context (Expr);
1616 -- If the indexed component appears in an object renaming declaration
1617 -- then we do not want to try to evaluate it, since in this case we
1618 -- need the identity of the array element.
1620 if Nkind (Parent (N)) = N_Object_Renaming_Declaration then
1623 -- Similarly if the indexed component appears as the prefix of an
1624 -- attribute we don't want to evaluate it, because at least for
1625 -- some cases of attributes we need the identify (e.g. Access, Size)
1627 elsif Nkind (Parent (N)) = N_Attribute_Reference then
1631 -- Note: there are other cases, such as the left side of an assignment,
1632 -- or an OUT parameter for a call, where the replacement results in the
1633 -- illegal use of a constant, But these cases are illegal in the first
1634 -- place, so the replacement, though silly, is harmless.
1636 -- Now see if this is a constant array reference
1638 if List_Length (Expressions (N)) = 1
1639 and then Is_Entity_Name (Prefix (N))
1640 and then Ekind (Entity (Prefix (N))) = E_Constant
1641 and then Present (Constant_Value (Entity (Prefix (N))))
1644 Loc : constant Source_Ptr := Sloc (N);
1645 Arr : constant Node_Id := Constant_Value (Entity (Prefix (N)));
1646 Sub : constant Node_Id := First (Expressions (N));
1652 -- Linear one's origin subscript value for array reference
1655 -- Lower bound of the first array index
1658 -- Value from constant array
1661 Atyp := Etype (Arr);
1663 if Is_Access_Type (Atyp) then
1664 Atyp := Designated_Type (Atyp);
1667 -- If we have an array type (we should have but perhaps there
1668 -- are error cases where this is not the case), then see if we
1669 -- can do a constant evaluation of the array reference.
1671 if Is_Array_Type (Atyp) then
1672 if Ekind (Atyp) = E_String_Literal_Subtype then
1673 Lbd := String_Literal_Low_Bound (Atyp);
1675 Lbd := Type_Low_Bound (Etype (First_Index (Atyp)));
1678 if Compile_Time_Known_Value (Sub)
1679 and then Nkind (Arr) = N_Aggregate
1680 and then Compile_Time_Known_Value (Lbd)
1681 and then Is_Discrete_Type (Component_Type (Atyp))
1683 Lin := UI_To_Int (Expr_Value (Sub) - Expr_Value (Lbd)) + 1;
1685 if List_Length (Expressions (Arr)) >= Lin then
1686 Elm := Pick (Expressions (Arr), Lin);
1688 -- If the resulting expression is compile time known,
1689 -- then we can rewrite the indexed component with this
1690 -- value, being sure to mark the result as non-static.
1691 -- We also reset the Sloc, in case this generates an
1692 -- error later on (e.g. 136'Access).
1694 if Compile_Time_Known_Value (Elm) then
1695 Rewrite (N, Duplicate_Subexpr_No_Checks (Elm));
1696 Set_Is_Static_Expression (N, False);
1704 end Eval_Indexed_Component;
1706 --------------------------
1707 -- Eval_Integer_Literal --
1708 --------------------------
1710 -- Numeric literals are static (RM 4.9(1)), and have already been marked
1711 -- as static by the analyzer. The reason we did it that early is to allow
1712 -- the possibility of turning off the Is_Static_Expression flag after
1713 -- analysis, but before resolution, when integer literals are generated
1714 -- in the expander that do not correspond to static expressions.
1716 procedure Eval_Integer_Literal (N : Node_Id) is
1717 T : constant Entity_Id := Etype (N);
1719 function In_Any_Integer_Context return Boolean;
1720 -- If the literal is resolved with a specific type in a context
1721 -- where the expected type is Any_Integer, there are no range checks
1722 -- on the literal. By the time the literal is evaluated, it carries
1723 -- the type imposed by the enclosing expression, and we must recover
1724 -- the context to determine that Any_Integer is meant.
1726 ----------------------------
1727 -- To_Any_Integer_Context --
1728 ----------------------------
1730 function In_Any_Integer_Context return Boolean is
1731 Par : constant Node_Id := Parent (N);
1732 K : constant Node_Kind := Nkind (Par);
1735 -- Any_Integer also appears in digits specifications for real types,
1736 -- but those have bounds smaller that those of any integer base
1737 -- type, so we can safely ignore these cases.
1739 return K = N_Number_Declaration
1740 or else K = N_Attribute_Reference
1741 or else K = N_Attribute_Definition_Clause
1742 or else K = N_Modular_Type_Definition
1743 or else K = N_Signed_Integer_Type_Definition;
1744 end In_Any_Integer_Context;
1746 -- Start of processing for Eval_Integer_Literal
1750 -- If the literal appears in a non-expression context, then it is
1751 -- certainly appearing in a non-static context, so check it. This
1752 -- is actually a redundant check, since Check_Non_Static_Context
1753 -- would check it, but it seems worth while avoiding the call.
1755 if Nkind (Parent (N)) not in N_Subexpr
1756 and then not In_Any_Integer_Context
1758 Check_Non_Static_Context (N);
1761 -- Modular integer literals must be in their base range
1763 if Is_Modular_Integer_Type (T)
1764 and then Is_Out_Of_Range (N, Base_Type (T))
1768 end Eval_Integer_Literal;
1770 ---------------------
1771 -- Eval_Logical_Op --
1772 ---------------------
1774 -- Logical operations are static functions, so the result is potentially
1775 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
1777 procedure Eval_Logical_Op (N : Node_Id) is
1778 Left : constant Node_Id := Left_Opnd (N);
1779 Right : constant Node_Id := Right_Opnd (N);
1784 -- If not foldable we are done
1786 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
1792 -- Compile time evaluation of logical operation
1795 Left_Int : constant Uint := Expr_Value (Left);
1796 Right_Int : constant Uint := Expr_Value (Right);
1799 if Is_Modular_Integer_Type (Etype (N)) then
1801 Left_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
1802 Right_Bits : Bits (0 .. UI_To_Int (Esize (Etype (N))) - 1);
1805 To_Bits (Left_Int, Left_Bits);
1806 To_Bits (Right_Int, Right_Bits);
1808 -- Note: should really be able to use array ops instead of
1809 -- these loops, but they weren't working at the time ???
1811 if Nkind (N) = N_Op_And then
1812 for J in Left_Bits'Range loop
1813 Left_Bits (J) := Left_Bits (J) and Right_Bits (J);
1816 elsif Nkind (N) = N_Op_Or then
1817 for J in Left_Bits'Range loop
1818 Left_Bits (J) := Left_Bits (J) or Right_Bits (J);
1822 pragma Assert (Nkind (N) = N_Op_Xor);
1824 for J in Left_Bits'Range loop
1825 Left_Bits (J) := Left_Bits (J) xor Right_Bits (J);
1829 Fold_Uint (N, From_Bits (Left_Bits, Etype (N)), Stat);
1833 pragma Assert (Is_Boolean_Type (Etype (N)));
1835 if Nkind (N) = N_Op_And then
1837 Test (Is_True (Left_Int) and then Is_True (Right_Int)), Stat);
1839 elsif Nkind (N) = N_Op_Or then
1841 Test (Is_True (Left_Int) or else Is_True (Right_Int)), Stat);
1844 pragma Assert (Nkind (N) = N_Op_Xor);
1846 Test (Is_True (Left_Int) xor Is_True (Right_Int)), Stat);
1850 end Eval_Logical_Op;
1852 ------------------------
1853 -- Eval_Membership_Op --
1854 ------------------------
1856 -- A membership test is potentially static if the expression is static,
1857 -- and the range is a potentially static range, or is a subtype mark
1858 -- denoting a static subtype (RM 4.9(12)).
1860 procedure Eval_Membership_Op (N : Node_Id) is
1861 Left : constant Node_Id := Left_Opnd (N);
1862 Right : constant Node_Id := Right_Opnd (N);
1871 -- Ignore if error in either operand, except to make sure that
1872 -- Any_Type is properly propagated to avoid junk cascaded errors.
1874 if Etype (Left) = Any_Type
1875 or else Etype (Right) = Any_Type
1877 Set_Etype (N, Any_Type);
1881 -- Case of right operand is a subtype name
1883 if Is_Entity_Name (Right) then
1884 Def_Id := Entity (Right);
1886 if (Is_Scalar_Type (Def_Id) or else Is_String_Type (Def_Id))
1887 and then Is_OK_Static_Subtype (Def_Id)
1889 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
1891 if not Fold or else not Stat then
1895 Check_Non_Static_Context (Left);
1899 -- For string membership tests we will check the length
1902 if not Is_String_Type (Def_Id) then
1903 Lo := Type_Low_Bound (Def_Id);
1904 Hi := Type_High_Bound (Def_Id);
1911 -- Case of right operand is a range
1914 if Is_Static_Range (Right) then
1915 Test_Expression_Is_Foldable (N, Left, Stat, Fold);
1917 if not Fold or else not Stat then
1920 -- If one bound of range raises CE, then don't try to fold
1922 elsif not Is_OK_Static_Range (Right) then
1923 Check_Non_Static_Context (Left);
1928 Check_Non_Static_Context (Left);
1932 -- Here we know range is an OK static range
1934 Lo := Low_Bound (Right);
1935 Hi := High_Bound (Right);
1938 -- For strings we check that the length of the string expression is
1939 -- compatible with the string subtype if the subtype is constrained,
1940 -- or if unconstrained then the test is always true.
1942 if Is_String_Type (Etype (Right)) then
1943 if not Is_Constrained (Etype (Right)) then
1948 Typlen : constant Uint := String_Type_Len (Etype (Right));
1949 Strlen : constant Uint :=
1950 UI_From_Int (String_Length (Strval (Get_String_Val (Left))));
1952 Result := (Typlen = Strlen);
1956 -- Fold the membership test. We know we have a static range and Lo
1957 -- and Hi are set to the expressions for the end points of this range.
1959 elsif Is_Real_Type (Etype (Right)) then
1961 Leftval : constant Ureal := Expr_Value_R (Left);
1964 Result := Expr_Value_R (Lo) <= Leftval
1965 and then Leftval <= Expr_Value_R (Hi);
1970 Leftval : constant Uint := Expr_Value (Left);
1973 Result := Expr_Value (Lo) <= Leftval
1974 and then Leftval <= Expr_Value (Hi);
1978 if Nkind (N) = N_Not_In then
1979 Result := not Result;
1982 Fold_Uint (N, Test (Result), True);
1983 Warn_On_Known_Condition (N);
1984 end Eval_Membership_Op;
1986 ------------------------
1987 -- Eval_Named_Integer --
1988 ------------------------
1990 procedure Eval_Named_Integer (N : Node_Id) is
1993 Expr_Value (Expression (Declaration_Node (Entity (N)))), True);
1994 end Eval_Named_Integer;
1996 ---------------------
1997 -- Eval_Named_Real --
1998 ---------------------
2000 procedure Eval_Named_Real (N : Node_Id) is
2003 Expr_Value_R (Expression (Declaration_Node (Entity (N)))), True);
2004 end Eval_Named_Real;
2010 -- Exponentiation is a static functions, so the result is potentially
2011 -- static if both operands are potentially static (RM 4.9(7), 4.9(20)).
2013 procedure Eval_Op_Expon (N : Node_Id) is
2014 Left : constant Node_Id := Left_Opnd (N);
2015 Right : constant Node_Id := Right_Opnd (N);
2020 -- If not foldable we are done
2022 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2028 -- Fold exponentiation operation
2031 Right_Int : constant Uint := Expr_Value (Right);
2036 if Is_Integer_Type (Etype (Left)) then
2038 Left_Int : constant Uint := Expr_Value (Left);
2042 -- Exponentiation of an integer raises the exception
2043 -- Constraint_Error for a negative exponent (RM 4.5.6)
2045 if Right_Int < 0 then
2046 Apply_Compile_Time_Constraint_Error
2047 (N, "integer exponent negative",
2048 CE_Range_Check_Failed,
2053 if OK_Bits (N, Num_Bits (Left_Int) * Right_Int) then
2054 Result := Left_Int ** Right_Int;
2059 if Is_Modular_Integer_Type (Etype (N)) then
2060 Result := Result mod Modulus (Etype (N));
2063 Fold_Uint (N, Result, Stat);
2071 Left_Real : constant Ureal := Expr_Value_R (Left);
2074 -- Cannot have a zero base with a negative exponent
2076 if UR_Is_Zero (Left_Real) then
2078 if Right_Int < 0 then
2079 Apply_Compile_Time_Constraint_Error
2080 (N, "zero ** negative integer",
2081 CE_Range_Check_Failed,
2085 Fold_Ureal (N, Ureal_0, Stat);
2089 Fold_Ureal (N, Left_Real ** Right_Int, Stat);
2100 -- The not operation is a static functions, so the result is potentially
2101 -- static if the operand is potentially static (RM 4.9(7), 4.9(20)).
2103 procedure Eval_Op_Not (N : Node_Id) is
2104 Right : constant Node_Id := Right_Opnd (N);
2109 -- If not foldable we are done
2111 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2117 -- Fold not operation
2120 Rint : constant Uint := Expr_Value (Right);
2121 Typ : constant Entity_Id := Etype (N);
2124 -- Negation is equivalent to subtracting from the modulus minus
2125 -- one. For a binary modulus this is equivalent to the ones-
2126 -- component of the original value. For non-binary modulus this
2127 -- is an arbitrary but consistent definition.
2129 if Is_Modular_Integer_Type (Typ) then
2130 Fold_Uint (N, Modulus (Typ) - 1 - Rint, Stat);
2133 pragma Assert (Is_Boolean_Type (Typ));
2134 Fold_Uint (N, Test (not Is_True (Rint)), Stat);
2137 Set_Is_Static_Expression (N, Stat);
2141 -------------------------------
2142 -- Eval_Qualified_Expression --
2143 -------------------------------
2145 -- A qualified expression is potentially static if its subtype mark denotes
2146 -- a static subtype and its expression is potentially static (RM 4.9 (11)).
2148 procedure Eval_Qualified_Expression (N : Node_Id) is
2149 Operand : constant Node_Id := Expression (N);
2150 Target_Type : constant Entity_Id := Entity (Subtype_Mark (N));
2157 -- Can only fold if target is string or scalar and subtype is static
2158 -- Also, do not fold if our parent is an allocator (this is because
2159 -- the qualified expression is really part of the syntactic structure
2160 -- of an allocator, and we do not want to end up with something that
2161 -- corresponds to "new 1" where the 1 is the result of folding a
2162 -- qualified expression).
2164 if not Is_Static_Subtype (Target_Type)
2165 or else Nkind (Parent (N)) = N_Allocator
2167 Check_Non_Static_Context (Operand);
2169 -- If operand is known to raise constraint_error, set the
2170 -- flag on the expression so it does not get optimized away.
2172 if Nkind (Operand) = N_Raise_Constraint_Error then
2173 Set_Raises_Constraint_Error (N);
2179 -- If not foldable we are done
2181 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2186 -- Don't try fold if target type has constraint error bounds
2188 elsif not Is_OK_Static_Subtype (Target_Type) then
2189 Set_Raises_Constraint_Error (N);
2193 -- Here we will fold, save Print_In_Hex indication
2195 Hex := Nkind (Operand) = N_Integer_Literal
2196 and then Print_In_Hex (Operand);
2198 -- Fold the result of qualification
2200 if Is_Discrete_Type (Target_Type) then
2201 Fold_Uint (N, Expr_Value (Operand), Stat);
2203 -- Preserve Print_In_Hex indication
2205 if Hex and then Nkind (N) = N_Integer_Literal then
2206 Set_Print_In_Hex (N);
2209 elsif Is_Real_Type (Target_Type) then
2210 Fold_Ureal (N, Expr_Value_R (Operand), Stat);
2213 Fold_Str (N, Strval (Get_String_Val (Operand)), Stat);
2216 Set_Is_Static_Expression (N, False);
2218 Check_String_Literal_Length (N, Target_Type);
2224 -- The expression may be foldable but not static
2226 Set_Is_Static_Expression (N, Stat);
2228 if Is_Out_Of_Range (N, Etype (N)) then
2231 end Eval_Qualified_Expression;
2233 -----------------------
2234 -- Eval_Real_Literal --
2235 -----------------------
2237 -- Numeric literals are static (RM 4.9(1)), and have already been marked
2238 -- as static by the analyzer. The reason we did it that early is to allow
2239 -- the possibility of turning off the Is_Static_Expression flag after
2240 -- analysis, but before resolution, when integer literals are generated
2241 -- in the expander that do not correspond to static expressions.
2243 procedure Eval_Real_Literal (N : Node_Id) is
2244 PK : constant Node_Kind := Nkind (Parent (N));
2247 -- If the literal appears in a non-expression context
2248 -- and not as part of a number declaration, then it is
2249 -- appearing in a non-static context, so check it.
2251 if PK not in N_Subexpr and then PK /= N_Number_Declaration then
2252 Check_Non_Static_Context (N);
2254 end Eval_Real_Literal;
2256 ------------------------
2257 -- Eval_Relational_Op --
2258 ------------------------
2260 -- Relational operations are static functions, so the result is static
2261 -- if both operands are static (RM 4.9(7), 4.9(20)).
2263 procedure Eval_Relational_Op (N : Node_Id) is
2264 Left : constant Node_Id := Left_Opnd (N);
2265 Right : constant Node_Id := Right_Opnd (N);
2266 Typ : constant Entity_Id := Etype (Left);
2272 -- One special case to deal with first. If we can tell that
2273 -- the result will be false because the lengths of one or
2274 -- more index subtypes are compile time known and different,
2275 -- then we can replace the entire result by False. We only
2276 -- do this for one dimensional arrays, because the case of
2277 -- multi-dimensional arrays is rare and too much trouble!
2278 -- If one of the operands is an illegal aggregate, its type
2279 -- might still be an arbitrary composite type, so nothing to do.
2281 if Is_Array_Type (Typ)
2282 and then Typ /= Any_Composite
2283 and then Number_Dimensions (Typ) = 1
2284 and then (Nkind (N) = N_Op_Eq or else Nkind (N) = N_Op_Ne)
2286 if Raises_Constraint_Error (Left)
2287 or else Raises_Constraint_Error (Right)
2293 procedure Get_Static_Length (Op : Node_Id; Len : out Uint);
2294 -- If Op is an expression for a constrained array with a known
2295 -- at compile time length, then Len is set to this (non-negative
2296 -- length). Otherwise Len is set to minus 1.
2298 -----------------------
2299 -- Get_Static_Length --
2300 -----------------------
2302 procedure Get_Static_Length (Op : Node_Id; Len : out Uint) is
2306 if Nkind (Op) = N_String_Literal then
2307 Len := UI_From_Int (String_Length (Strval (Op)));
2309 elsif not Is_Constrained (Etype (Op)) then
2310 Len := Uint_Minus_1;
2313 T := Etype (First_Index (Etype (Op)));
2315 if Is_Discrete_Type (T)
2317 Compile_Time_Known_Value (Type_Low_Bound (T))
2319 Compile_Time_Known_Value (Type_High_Bound (T))
2321 Len := UI_Max (Uint_0,
2322 Expr_Value (Type_High_Bound (T)) -
2323 Expr_Value (Type_Low_Bound (T)) + 1);
2325 Len := Uint_Minus_1;
2328 end Get_Static_Length;
2334 Get_Static_Length (Left, Len_L);
2335 Get_Static_Length (Right, Len_R);
2337 if Len_L /= Uint_Minus_1
2338 and then Len_R /= Uint_Minus_1
2339 and then Len_L /= Len_R
2341 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2342 Warn_On_Known_Condition (N);
2347 -- Another special case: comparisons of access types, where one or both
2348 -- operands are known to be null, so the result can be determined.
2350 elsif Is_Access_Type (Typ) then
2351 if Known_Null (Left) then
2352 if Known_Null (Right) then
2353 Fold_Uint (N, Test (Nkind (N) = N_Op_Eq), False);
2354 Warn_On_Known_Condition (N);
2357 elsif Known_Non_Null (Right) then
2358 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2359 Warn_On_Known_Condition (N);
2363 elsif Known_Non_Null (Left) then
2364 if Known_Null (Right) then
2365 Fold_Uint (N, Test (Nkind (N) = N_Op_Ne), False);
2366 Warn_On_Known_Condition (N);
2372 -- Can only fold if type is scalar (don't fold string ops)
2374 if not Is_Scalar_Type (Typ) then
2375 Check_Non_Static_Context (Left);
2376 Check_Non_Static_Context (Right);
2380 -- If not foldable we are done
2382 Test_Expression_Is_Foldable (N, Left, Right, Stat, Fold);
2388 -- Integer and Enumeration (discrete) type cases
2390 if Is_Discrete_Type (Typ) then
2392 Left_Int : constant Uint := Expr_Value (Left);
2393 Right_Int : constant Uint := Expr_Value (Right);
2397 when N_Op_Eq => Result := Left_Int = Right_Int;
2398 when N_Op_Ne => Result := Left_Int /= Right_Int;
2399 when N_Op_Lt => Result := Left_Int < Right_Int;
2400 when N_Op_Le => Result := Left_Int <= Right_Int;
2401 when N_Op_Gt => Result := Left_Int > Right_Int;
2402 when N_Op_Ge => Result := Left_Int >= Right_Int;
2405 raise Program_Error;
2408 Fold_Uint (N, Test (Result), Stat);
2414 pragma Assert (Is_Real_Type (Typ));
2417 Left_Real : constant Ureal := Expr_Value_R (Left);
2418 Right_Real : constant Ureal := Expr_Value_R (Right);
2422 when N_Op_Eq => Result := (Left_Real = Right_Real);
2423 when N_Op_Ne => Result := (Left_Real /= Right_Real);
2424 when N_Op_Lt => Result := (Left_Real < Right_Real);
2425 when N_Op_Le => Result := (Left_Real <= Right_Real);
2426 when N_Op_Gt => Result := (Left_Real > Right_Real);
2427 when N_Op_Ge => Result := (Left_Real >= Right_Real);
2430 raise Program_Error;
2433 Fold_Uint (N, Test (Result), Stat);
2437 Warn_On_Known_Condition (N);
2438 end Eval_Relational_Op;
2444 -- Shift operations are intrinsic operations that can never be static,
2445 -- so the only processing required is to perform the required check for
2446 -- a non static context for the two operands.
2448 -- Actually we could do some compile time evaluation here some time ???
2450 procedure Eval_Shift (N : Node_Id) is
2452 Check_Non_Static_Context (Left_Opnd (N));
2453 Check_Non_Static_Context (Right_Opnd (N));
2456 ------------------------
2457 -- Eval_Short_Circuit --
2458 ------------------------
2460 -- A short circuit operation is potentially static if both operands
2461 -- are potentially static (RM 4.9 (13))
2463 procedure Eval_Short_Circuit (N : Node_Id) is
2464 Kind : constant Node_Kind := Nkind (N);
2465 Left : constant Node_Id := Left_Opnd (N);
2466 Right : constant Node_Id := Right_Opnd (N);
2468 Rstat : constant Boolean :=
2469 Is_Static_Expression (Left)
2470 and then Is_Static_Expression (Right);
2473 -- Short circuit operations are never static in Ada 83
2475 if Ada_Version = Ada_83
2476 and then Comes_From_Source (N)
2478 Check_Non_Static_Context (Left);
2479 Check_Non_Static_Context (Right);
2483 -- Now look at the operands, we can't quite use the normal call to
2484 -- Test_Expression_Is_Foldable here because short circuit operations
2485 -- are a special case, they can still be foldable, even if the right
2486 -- operand raises constraint error.
2488 -- If either operand is Any_Type, just propagate to result and
2489 -- do not try to fold, this prevents cascaded errors.
2491 if Etype (Left) = Any_Type or else Etype (Right) = Any_Type then
2492 Set_Etype (N, Any_Type);
2495 -- If left operand raises constraint error, then replace node N with
2496 -- the raise constraint error node, and we are obviously not foldable.
2497 -- Is_Static_Expression is set from the two operands in the normal way,
2498 -- and we check the right operand if it is in a non-static context.
2500 elsif Raises_Constraint_Error (Left) then
2502 Check_Non_Static_Context (Right);
2505 Rewrite_In_Raise_CE (N, Left);
2506 Set_Is_Static_Expression (N, Rstat);
2509 -- If the result is not static, then we won't in any case fold
2511 elsif not Rstat then
2512 Check_Non_Static_Context (Left);
2513 Check_Non_Static_Context (Right);
2517 -- Here the result is static, note that, unlike the normal processing
2518 -- in Test_Expression_Is_Foldable, we did *not* check above to see if
2519 -- the right operand raises constraint error, that's because it is not
2520 -- significant if the left operand is decisive.
2522 Set_Is_Static_Expression (N);
2524 -- It does not matter if the right operand raises constraint error if
2525 -- it will not be evaluated. So deal specially with the cases where
2526 -- the right operand is not evaluated. Note that we will fold these
2527 -- cases even if the right operand is non-static, which is fine, but
2528 -- of course in these cases the result is not potentially static.
2530 Left_Int := Expr_Value (Left);
2532 if (Kind = N_And_Then and then Is_False (Left_Int))
2533 or else (Kind = N_Or_Else and Is_True (Left_Int))
2535 Fold_Uint (N, Left_Int, Rstat);
2539 -- If first operand not decisive, then it does matter if the right
2540 -- operand raises constraint error, since it will be evaluated, so
2541 -- we simply replace the node with the right operand. Note that this
2542 -- properly propagates Is_Static_Expression and Raises_Constraint_Error
2543 -- (both are set to True in Right).
2545 if Raises_Constraint_Error (Right) then
2546 Rewrite_In_Raise_CE (N, Right);
2547 Check_Non_Static_Context (Left);
2551 -- Otherwise the result depends on the right operand
2553 Fold_Uint (N, Expr_Value (Right), Rstat);
2555 end Eval_Short_Circuit;
2561 -- Slices can never be static, so the only processing required is to
2562 -- check for non-static context if an explicit range is given.
2564 procedure Eval_Slice (N : Node_Id) is
2565 Drange : constant Node_Id := Discrete_Range (N);
2567 if Nkind (Drange) = N_Range then
2568 Check_Non_Static_Context (Low_Bound (Drange));
2569 Check_Non_Static_Context (High_Bound (Drange));
2573 -------------------------
2574 -- Eval_String_Literal --
2575 -------------------------
2577 procedure Eval_String_Literal (N : Node_Id) is
2578 Typ : constant Entity_Id := Etype (N);
2579 Bas : constant Entity_Id := Base_Type (Typ);
2585 -- Nothing to do if error type (handles cases like default expressions
2586 -- or generics where we have not yet fully resolved the type)
2588 if Bas = Any_Type or else Bas = Any_String then
2592 -- String literals are static if the subtype is static (RM 4.9(2)), so
2593 -- reset the static expression flag (it was set unconditionally in
2594 -- Analyze_String_Literal) if the subtype is non-static. We tell if
2595 -- the subtype is static by looking at the lower bound.
2597 if Ekind (Typ) = E_String_Literal_Subtype then
2598 if not Is_OK_Static_Expression (String_Literal_Low_Bound (Typ)) then
2599 Set_Is_Static_Expression (N, False);
2603 -- Here if Etype of string literal is normal Etype (not yet possible,
2604 -- but may be possible in future!)
2606 elsif not Is_OK_Static_Expression
2607 (Type_Low_Bound (Etype (First_Index (Typ))))
2609 Set_Is_Static_Expression (N, False);
2613 -- If original node was a type conversion, then result if non-static
2615 if Nkind (Original_Node (N)) = N_Type_Conversion then
2616 Set_Is_Static_Expression (N, False);
2620 -- Test for illegal Ada 95 cases. A string literal is illegal in
2621 -- Ada 95 if its bounds are outside the index base type and this
2622 -- index type is static. This can happen in only two ways. Either
2623 -- the string literal is too long, or it is null, and the lower
2624 -- bound is type'First. In either case it is the upper bound that
2625 -- is out of range of the index type.
2627 if Ada_Version >= Ada_95 then
2628 if Root_Type (Bas) = Standard_String
2630 Root_Type (Bas) = Standard_Wide_String
2632 Xtp := Standard_Positive;
2634 Xtp := Etype (First_Index (Bas));
2637 if Ekind (Typ) = E_String_Literal_Subtype then
2638 Lo := String_Literal_Low_Bound (Typ);
2640 Lo := Type_Low_Bound (Etype (First_Index (Typ)));
2643 Len := String_Length (Strval (N));
2645 if UI_From_Int (Len) > String_Type_Len (Bas) then
2646 Apply_Compile_Time_Constraint_Error
2647 (N, "string literal too long for}", CE_Length_Check_Failed,
2649 Typ => First_Subtype (Bas));
2652 and then not Is_Generic_Type (Xtp)
2654 Expr_Value (Lo) = Expr_Value (Type_Low_Bound (Base_Type (Xtp)))
2656 Apply_Compile_Time_Constraint_Error
2657 (N, "null string literal not allowed for}",
2658 CE_Length_Check_Failed,
2660 Typ => First_Subtype (Bas));
2663 end Eval_String_Literal;
2665 --------------------------
2666 -- Eval_Type_Conversion --
2667 --------------------------
2669 -- A type conversion is potentially static if its subtype mark is for a
2670 -- static scalar subtype, and its operand expression is potentially static
2673 procedure Eval_Type_Conversion (N : Node_Id) is
2674 Operand : constant Node_Id := Expression (N);
2675 Source_Type : constant Entity_Id := Etype (Operand);
2676 Target_Type : constant Entity_Id := Etype (N);
2681 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean;
2682 -- Returns true if type T is an integer type, or if it is a
2683 -- fixed-point type to be treated as an integer (i.e. the flag
2684 -- Conversion_OK is set on the conversion node).
2686 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean;
2687 -- Returns true if type T is a floating-point type, or if it is a
2688 -- fixed-point type that is not to be treated as an integer (i.e. the
2689 -- flag Conversion_OK is not set on the conversion node).
2691 ------------------------------
2692 -- To_Be_Treated_As_Integer --
2693 ------------------------------
2695 function To_Be_Treated_As_Integer (T : Entity_Id) return Boolean is
2699 or else (Is_Fixed_Point_Type (T) and then Conversion_OK (N));
2700 end To_Be_Treated_As_Integer;
2702 ---------------------------
2703 -- To_Be_Treated_As_Real --
2704 ---------------------------
2706 function To_Be_Treated_As_Real (T : Entity_Id) return Boolean is
2709 Is_Floating_Point_Type (T)
2710 or else (Is_Fixed_Point_Type (T) and then not Conversion_OK (N));
2711 end To_Be_Treated_As_Real;
2713 -- Start of processing for Eval_Type_Conversion
2716 -- Cannot fold if target type is non-static or if semantic error
2718 if not Is_Static_Subtype (Target_Type) then
2719 Check_Non_Static_Context (Operand);
2722 elsif Error_Posted (N) then
2726 -- If not foldable we are done
2728 Test_Expression_Is_Foldable (N, Operand, Stat, Fold);
2733 -- Don't try fold if target type has constraint error bounds
2735 elsif not Is_OK_Static_Subtype (Target_Type) then
2736 Set_Raises_Constraint_Error (N);
2740 -- Remaining processing depends on operand types. Note that in the
2741 -- following type test, fixed-point counts as real unless the flag
2742 -- Conversion_OK is set, in which case it counts as integer.
2744 -- Fold conversion, case of string type. The result is not static
2746 if Is_String_Type (Target_Type) then
2747 Fold_Str (N, Strval (Get_String_Val (Operand)), Static => False);
2751 -- Fold conversion, case of integer target type
2753 elsif To_Be_Treated_As_Integer (Target_Type) then
2758 -- Integer to integer conversion
2760 if To_Be_Treated_As_Integer (Source_Type) then
2761 Result := Expr_Value (Operand);
2763 -- Real to integer conversion
2766 Result := UR_To_Uint (Expr_Value_R (Operand));
2769 -- If fixed-point type (Conversion_OK must be set), then the
2770 -- result is logically an integer, but we must replace the
2771 -- conversion with the corresponding real literal, since the
2772 -- type from a semantic point of view is still fixed-point.
2774 if Is_Fixed_Point_Type (Target_Type) then
2776 (N, UR_From_Uint (Result) * Small_Value (Target_Type), Stat);
2778 -- Otherwise result is integer literal
2781 Fold_Uint (N, Result, Stat);
2785 -- Fold conversion, case of real target type
2787 elsif To_Be_Treated_As_Real (Target_Type) then
2792 if To_Be_Treated_As_Real (Source_Type) then
2793 Result := Expr_Value_R (Operand);
2795 Result := UR_From_Uint (Expr_Value (Operand));
2798 Fold_Ureal (N, Result, Stat);
2801 -- Enumeration types
2804 Fold_Uint (N, Expr_Value (Operand), Stat);
2807 if Is_Out_Of_Range (N, Etype (N)) then
2811 end Eval_Type_Conversion;
2817 -- Predefined unary operators are static functions (RM 4.9(20)) and thus
2818 -- are potentially static if the operand is potentially static (RM 4.9(7))
2820 procedure Eval_Unary_Op (N : Node_Id) is
2821 Right : constant Node_Id := Right_Opnd (N);
2826 -- If not foldable we are done
2828 Test_Expression_Is_Foldable (N, Right, Stat, Fold);
2834 -- Fold for integer case
2836 if Is_Integer_Type (Etype (N)) then
2838 Rint : constant Uint := Expr_Value (Right);
2842 -- In the case of modular unary plus and abs there is no need
2843 -- to adjust the result of the operation since if the original
2844 -- operand was in bounds the result will be in the bounds of the
2845 -- modular type. However, in the case of modular unary minus the
2846 -- result may go out of the bounds of the modular type and needs
2849 if Nkind (N) = N_Op_Plus then
2852 elsif Nkind (N) = N_Op_Minus then
2853 if Is_Modular_Integer_Type (Etype (N)) then
2854 Result := (-Rint) mod Modulus (Etype (N));
2860 pragma Assert (Nkind (N) = N_Op_Abs);
2864 Fold_Uint (N, Result, Stat);
2867 -- Fold for real case
2869 elsif Is_Real_Type (Etype (N)) then
2871 Rreal : constant Ureal := Expr_Value_R (Right);
2875 if Nkind (N) = N_Op_Plus then
2878 elsif Nkind (N) = N_Op_Minus then
2879 Result := UR_Negate (Rreal);
2882 pragma Assert (Nkind (N) = N_Op_Abs);
2883 Result := abs Rreal;
2886 Fold_Ureal (N, Result, Stat);
2891 -------------------------------
2892 -- Eval_Unchecked_Conversion --
2893 -------------------------------
2895 -- Unchecked conversions can never be static, so the only required
2896 -- processing is to check for a non-static context for the operand.
2898 procedure Eval_Unchecked_Conversion (N : Node_Id) is
2900 Check_Non_Static_Context (Expression (N));
2901 end Eval_Unchecked_Conversion;
2903 --------------------
2904 -- Expr_Rep_Value --
2905 --------------------
2907 function Expr_Rep_Value (N : Node_Id) return Uint is
2908 Kind : constant Node_Kind := Nkind (N);
2912 if Is_Entity_Name (N) then
2915 -- An enumeration literal that was either in the source or
2916 -- created as a result of static evaluation.
2918 if Ekind (Ent) = E_Enumeration_Literal then
2919 return Enumeration_Rep (Ent);
2921 -- A user defined static constant
2924 pragma Assert (Ekind (Ent) = E_Constant);
2925 return Expr_Rep_Value (Constant_Value (Ent));
2928 -- An integer literal that was either in the source or created
2929 -- as a result of static evaluation.
2931 elsif Kind = N_Integer_Literal then
2934 -- A real literal for a fixed-point type. This must be the fixed-point
2935 -- case, either the literal is of a fixed-point type, or it is a bound
2936 -- of a fixed-point type, with type universal real. In either case we
2937 -- obtain the desired value from Corresponding_Integer_Value.
2939 elsif Kind = N_Real_Literal then
2940 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
2941 return Corresponding_Integer_Value (N);
2943 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
2945 elsif Kind = N_Attribute_Reference
2946 and then Attribute_Name (N) = Name_Null_Parameter
2950 -- Otherwise must be character literal
2953 pragma Assert (Kind = N_Character_Literal);
2956 -- Since Character literals of type Standard.Character don't
2957 -- have any defining character literals built for them, they
2958 -- do not have their Entity set, so just use their Char
2959 -- code. Otherwise for user-defined character literals use
2960 -- their Pos value as usual which is the same as the Rep value.
2963 return Char_Literal_Value (N);
2965 return Enumeration_Rep (Ent);
2974 function Expr_Value (N : Node_Id) return Uint is
2975 Kind : constant Node_Kind := Nkind (N);
2976 CV_Ent : CV_Entry renames CV_Cache (Nat (N) mod CV_Cache_Size);
2981 -- If already in cache, then we know it's compile time known and we can
2982 -- return the value that was previously stored in the cache since
2983 -- compile time known values cannot change.
2985 if CV_Ent.N = N then
2989 -- Otherwise proceed to test value
2991 if Is_Entity_Name (N) then
2994 -- An enumeration literal that was either in the source or
2995 -- created as a result of static evaluation.
2997 if Ekind (Ent) = E_Enumeration_Literal then
2998 Val := Enumeration_Pos (Ent);
3000 -- A user defined static constant
3003 pragma Assert (Ekind (Ent) = E_Constant);
3004 Val := Expr_Value (Constant_Value (Ent));
3007 -- An integer literal that was either in the source or created
3008 -- as a result of static evaluation.
3010 elsif Kind = N_Integer_Literal then
3013 -- A real literal for a fixed-point type. This must be the fixed-point
3014 -- case, either the literal is of a fixed-point type, or it is a bound
3015 -- of a fixed-point type, with type universal real. In either case we
3016 -- obtain the desired value from Corresponding_Integer_Value.
3018 elsif Kind = N_Real_Literal then
3020 pragma Assert (Is_Fixed_Point_Type (Underlying_Type (Etype (N))));
3021 Val := Corresponding_Integer_Value (N);
3023 -- Peculiar VMS case, if we have xxx'Null_Parameter, return zero
3025 elsif Kind = N_Attribute_Reference
3026 and then Attribute_Name (N) = Name_Null_Parameter
3030 -- Otherwise must be character literal
3033 pragma Assert (Kind = N_Character_Literal);
3036 -- Since Character literals of type Standard.Character don't
3037 -- have any defining character literals built for them, they
3038 -- do not have their Entity set, so just use their Char
3039 -- code. Otherwise for user-defined character literals use
3040 -- their Pos value as usual.
3043 Val := Char_Literal_Value (N);
3045 Val := Enumeration_Pos (Ent);
3049 -- Come here with Val set to value to be returned, set cache
3060 function Expr_Value_E (N : Node_Id) return Entity_Id is
3061 Ent : constant Entity_Id := Entity (N);
3064 if Ekind (Ent) = E_Enumeration_Literal then
3067 pragma Assert (Ekind (Ent) = E_Constant);
3068 return Expr_Value_E (Constant_Value (Ent));
3076 function Expr_Value_R (N : Node_Id) return Ureal is
3077 Kind : constant Node_Kind := Nkind (N);
3082 if Kind = N_Real_Literal then
3085 elsif Kind = N_Identifier or else Kind = N_Expanded_Name then
3087 pragma Assert (Ekind (Ent) = E_Constant);
3088 return Expr_Value_R (Constant_Value (Ent));
3090 elsif Kind = N_Integer_Literal then
3091 return UR_From_Uint (Expr_Value (N));
3093 -- Strange case of VAX literals, which are at this stage transformed
3094 -- into Vax_Type!x_To_y(IEEE_Literal). See Expand_N_Real_Literal in
3095 -- Exp_Vfpt for further details.
3097 elsif Vax_Float (Etype (N))
3098 and then Nkind (N) = N_Unchecked_Type_Conversion
3100 Expr := Expression (N);
3102 if Nkind (Expr) = N_Function_Call
3103 and then Present (Parameter_Associations (Expr))
3105 Expr := First (Parameter_Associations (Expr));
3107 if Nkind (Expr) = N_Real_Literal then
3108 return Realval (Expr);
3112 -- Peculiar VMS case, if we have xxx'Null_Parameter, return 0.0
3114 elsif Kind = N_Attribute_Reference
3115 and then Attribute_Name (N) = Name_Null_Parameter
3120 -- If we fall through, we have a node that cannot be interepreted
3121 -- as a compile time constant. That is definitely an error.
3123 raise Program_Error;
3130 function Expr_Value_S (N : Node_Id) return Node_Id is
3132 if Nkind (N) = N_String_Literal then
3135 pragma Assert (Ekind (Entity (N)) = E_Constant);
3136 return Expr_Value_S (Constant_Value (Entity (N)));
3140 --------------------------
3141 -- Flag_Non_Static_Expr --
3142 --------------------------
3144 procedure Flag_Non_Static_Expr (Msg : String; Expr : Node_Id) is
3146 if Error_Posted (Expr) and then not All_Errors_Mode then
3149 Error_Msg_F (Msg, Expr);
3150 Why_Not_Static (Expr);
3152 end Flag_Non_Static_Expr;
3158 procedure Fold_Str (N : Node_Id; Val : String_Id; Static : Boolean) is
3159 Loc : constant Source_Ptr := Sloc (N);
3160 Typ : constant Entity_Id := Etype (N);
3163 Rewrite (N, Make_String_Literal (Loc, Strval => Val));
3165 -- We now have the literal with the right value, both the actual type
3166 -- and the expected type of this literal are taken from the expression
3167 -- that was evaluated.
3170 Set_Is_Static_Expression (N, Static);
3179 procedure Fold_Uint (N : Node_Id; Val : Uint; Static : Boolean) is
3180 Loc : constant Source_Ptr := Sloc (N);
3181 Typ : Entity_Id := Etype (N);
3185 -- If we are folding a named number, retain the entity in the
3186 -- literal, for ASIS use.
3188 if Is_Entity_Name (N)
3189 and then Ekind (Entity (N)) = E_Named_Integer
3196 if Is_Private_Type (Typ) then
3197 Typ := Full_View (Typ);
3200 -- For a result of type integer, subsitute an N_Integer_Literal node
3201 -- for the result of the compile time evaluation of the expression.
3203 if Is_Integer_Type (Typ) then
3204 Rewrite (N, Make_Integer_Literal (Loc, Val));
3205 Set_Original_Entity (N, Ent);
3207 -- Otherwise we have an enumeration type, and we substitute either
3208 -- an N_Identifier or N_Character_Literal to represent the enumeration
3209 -- literal corresponding to the given value, which must always be in
3210 -- range, because appropriate tests have already been made for this.
3212 else pragma Assert (Is_Enumeration_Type (Typ));
3213 Rewrite (N, Get_Enum_Lit_From_Pos (Etype (N), Val, Loc));
3216 -- We now have the literal with the right value, both the actual type
3217 -- and the expected type of this literal are taken from the expression
3218 -- that was evaluated.
3221 Set_Is_Static_Expression (N, Static);
3230 procedure Fold_Ureal (N : Node_Id; Val : Ureal; Static : Boolean) is
3231 Loc : constant Source_Ptr := Sloc (N);
3232 Typ : constant Entity_Id := Etype (N);
3236 -- If we are folding a named number, retain the entity in the
3237 -- literal, for ASIS use.
3239 if Is_Entity_Name (N)
3240 and then Ekind (Entity (N)) = E_Named_Real
3247 Rewrite (N, Make_Real_Literal (Loc, Realval => Val));
3248 Set_Original_Entity (N, Ent);
3250 -- Both the actual and expected type comes from the original expression
3253 Set_Is_Static_Expression (N, Static);
3262 function From_Bits (B : Bits; T : Entity_Id) return Uint is
3266 for J in 0 .. B'Last loop
3272 if Non_Binary_Modulus (T) then
3273 V := V mod Modulus (T);
3279 --------------------
3280 -- Get_String_Val --
3281 --------------------
3283 function Get_String_Val (N : Node_Id) return Node_Id is
3285 if Nkind (N) = N_String_Literal then
3288 elsif Nkind (N) = N_Character_Literal then
3292 pragma Assert (Is_Entity_Name (N));
3293 return Get_String_Val (Constant_Value (Entity (N)));
3301 procedure Initialize is
3303 CV_Cache := (others => (Node_High_Bound, Uint_0));
3306 --------------------
3307 -- In_Subrange_Of --
3308 --------------------
3310 function In_Subrange_Of
3313 Fixed_Int : Boolean := False) return Boolean
3322 if T1 = T2 or else Is_Subtype_Of (T1, T2) then
3325 -- Never in range if both types are not scalar. Don't know if this can
3326 -- actually happen, but just in case.
3328 elsif not Is_Scalar_Type (T1) or else not Is_Scalar_Type (T1) then
3332 L1 := Type_Low_Bound (T1);
3333 H1 := Type_High_Bound (T1);
3335 L2 := Type_Low_Bound (T2);
3336 H2 := Type_High_Bound (T2);
3338 -- Check bounds to see if comparison possible at compile time
3340 if Compile_Time_Compare (L1, L2) in Compare_GE
3342 Compile_Time_Compare (H1, H2) in Compare_LE
3347 -- If bounds not comparable at compile time, then the bounds of T2
3348 -- must be compile time known or we cannot answer the query.
3350 if not Compile_Time_Known_Value (L2)
3351 or else not Compile_Time_Known_Value (H2)
3356 -- If the bounds of T1 are know at compile time then use these
3357 -- ones, otherwise use the bounds of the base type (which are of
3358 -- course always static).
3360 if not Compile_Time_Known_Value (L1) then
3361 L1 := Type_Low_Bound (Base_Type (T1));
3364 if not Compile_Time_Known_Value (H1) then
3365 H1 := Type_High_Bound (Base_Type (T1));
3368 -- Fixed point types should be considered as such only if
3369 -- flag Fixed_Int is set to False.
3371 if Is_Floating_Point_Type (T1) or else Is_Floating_Point_Type (T2)
3372 or else (Is_Fixed_Point_Type (T1) and then not Fixed_Int)
3373 or else (Is_Fixed_Point_Type (T2) and then not Fixed_Int)
3376 Expr_Value_R (L2) <= Expr_Value_R (L1)
3378 Expr_Value_R (H2) >= Expr_Value_R (H1);
3382 Expr_Value (L2) <= Expr_Value (L1)
3384 Expr_Value (H2) >= Expr_Value (H1);
3389 -- If any exception occurs, it means that we have some bug in the compiler
3390 -- possibly triggered by a previous error, or by some unforseen peculiar
3391 -- occurrence. However, this is only an optimization attempt, so there is
3392 -- really no point in crashing the compiler. Instead we just decide, too
3393 -- bad, we can't figure out the answer in this case after all.
3398 -- Debug flag K disables this behavior (useful for debugging)
3400 if Debug_Flag_K then
3411 function Is_In_Range
3414 Fixed_Int : Boolean := False;
3415 Int_Real : Boolean := False) return Boolean
3421 -- Universal types have no range limits, so always in range
3423 if Typ = Universal_Integer or else Typ = Universal_Real then
3426 -- Never in range if not scalar type. Don't know if this can
3427 -- actually happen, but our spec allows it, so we must check!
3429 elsif not Is_Scalar_Type (Typ) then
3432 -- Never in range unless we have a compile time known value
3434 elsif not Compile_Time_Known_Value (N) then
3439 Lo : constant Node_Id := Type_Low_Bound (Typ);
3440 Hi : constant Node_Id := Type_High_Bound (Typ);
3441 LB_Known : constant Boolean := Compile_Time_Known_Value (Lo);
3442 UB_Known : constant Boolean := Compile_Time_Known_Value (Hi);
3445 -- Fixed point types should be considered as such only in
3446 -- flag Fixed_Int is set to False.
3448 if Is_Floating_Point_Type (Typ)
3449 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3452 Valr := Expr_Value_R (N);
3454 if LB_Known and then Valr >= Expr_Value_R (Lo)
3455 and then UB_Known and then Valr <= Expr_Value_R (Hi)
3463 Val := Expr_Value (N);
3465 if LB_Known and then Val >= Expr_Value (Lo)
3466 and then UB_Known and then Val <= Expr_Value (Hi)
3481 function Is_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3482 Typ : constant Entity_Id := Etype (Lo);
3485 if not Compile_Time_Known_Value (Lo)
3486 or else not Compile_Time_Known_Value (Hi)
3491 if Is_Discrete_Type (Typ) then
3492 return Expr_Value (Lo) > Expr_Value (Hi);
3495 pragma Assert (Is_Real_Type (Typ));
3496 return Expr_Value_R (Lo) > Expr_Value_R (Hi);
3500 -----------------------------
3501 -- Is_OK_Static_Expression --
3502 -----------------------------
3504 function Is_OK_Static_Expression (N : Node_Id) return Boolean is
3506 return Is_Static_Expression (N)
3507 and then not Raises_Constraint_Error (N);
3508 end Is_OK_Static_Expression;
3510 ------------------------
3511 -- Is_OK_Static_Range --
3512 ------------------------
3514 -- A static range is a range whose bounds are static expressions, or a
3515 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3516 -- We have already converted range attribute references, so we get the
3517 -- "or" part of this rule without needing a special test.
3519 function Is_OK_Static_Range (N : Node_Id) return Boolean is
3521 return Is_OK_Static_Expression (Low_Bound (N))
3522 and then Is_OK_Static_Expression (High_Bound (N));
3523 end Is_OK_Static_Range;
3525 --------------------------
3526 -- Is_OK_Static_Subtype --
3527 --------------------------
3529 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
3530 -- where neither bound raises constraint error when evaluated.
3532 function Is_OK_Static_Subtype (Typ : Entity_Id) return Boolean is
3533 Base_T : constant Entity_Id := Base_Type (Typ);
3534 Anc_Subt : Entity_Id;
3537 -- First a quick check on the non static subtype flag. As described
3538 -- in further detail in Einfo, this flag is not decisive in all cases,
3539 -- but if it is set, then the subtype is definitely non-static.
3541 if Is_Non_Static_Subtype (Typ) then
3545 Anc_Subt := Ancestor_Subtype (Typ);
3547 if Anc_Subt = Empty then
3551 if Is_Generic_Type (Root_Type (Base_T))
3552 or else Is_Generic_Actual_Type (Base_T)
3558 elsif Is_String_Type (Typ) then
3560 Ekind (Typ) = E_String_Literal_Subtype
3562 (Is_OK_Static_Subtype (Component_Type (Typ))
3563 and then Is_OK_Static_Subtype (Etype (First_Index (Typ))));
3567 elsif Is_Scalar_Type (Typ) then
3568 if Base_T = Typ then
3572 -- Scalar_Range (Typ) might be an N_Subtype_Indication, so
3573 -- use Get_Type_Low,High_Bound.
3575 return Is_OK_Static_Subtype (Anc_Subt)
3576 and then Is_OK_Static_Expression (Type_Low_Bound (Typ))
3577 and then Is_OK_Static_Expression (Type_High_Bound (Typ));
3580 -- Types other than string and scalar types are never static
3585 end Is_OK_Static_Subtype;
3587 ---------------------
3588 -- Is_Out_Of_Range --
3589 ---------------------
3591 function Is_Out_Of_Range
3594 Fixed_Int : Boolean := False;
3595 Int_Real : Boolean := False) return Boolean
3601 -- Universal types have no range limits, so always in range
3603 if Typ = Universal_Integer or else Typ = Universal_Real then
3606 -- Never out of range if not scalar type. Don't know if this can
3607 -- actually happen, but our spec allows it, so we must check!
3609 elsif not Is_Scalar_Type (Typ) then
3612 -- Never out of range if this is a generic type, since the bounds
3613 -- of generic types are junk. Note that if we only checked for
3614 -- static expressions (instead of compile time known values) below,
3615 -- we would not need this check, because values of a generic type
3616 -- can never be static, but they can be known at compile time.
3618 elsif Is_Generic_Type (Typ) then
3621 -- Never out of range unless we have a compile time known value
3623 elsif not Compile_Time_Known_Value (N) then
3628 Lo : constant Node_Id := Type_Low_Bound (Typ);
3629 Hi : constant Node_Id := Type_High_Bound (Typ);
3630 LB_Known : constant Boolean := Compile_Time_Known_Value (Lo);
3631 UB_Known : constant Boolean := Compile_Time_Known_Value (Hi);
3634 -- Real types (note that fixed-point types are not treated
3635 -- as being of a real type if the flag Fixed_Int is set,
3636 -- since in that case they are regarded as integer types).
3638 if Is_Floating_Point_Type (Typ)
3639 or else (Is_Fixed_Point_Type (Typ) and then not Fixed_Int)
3642 Valr := Expr_Value_R (N);
3644 if LB_Known and then Valr < Expr_Value_R (Lo) then
3647 elsif UB_Known and then Expr_Value_R (Hi) < Valr then
3655 Val := Expr_Value (N);
3657 if LB_Known and then Val < Expr_Value (Lo) then
3660 elsif UB_Known and then Expr_Value (Hi) < Val then
3669 end Is_Out_Of_Range;
3671 ---------------------
3672 -- Is_Static_Range --
3673 ---------------------
3675 -- A static range is a range whose bounds are static expressions, or a
3676 -- Range_Attribute_Reference equivalent to such a range (RM 4.9(26)).
3677 -- We have already converted range attribute references, so we get the
3678 -- "or" part of this rule without needing a special test.
3680 function Is_Static_Range (N : Node_Id) return Boolean is
3682 return Is_Static_Expression (Low_Bound (N))
3683 and then Is_Static_Expression (High_Bound (N));
3684 end Is_Static_Range;
3686 -----------------------
3687 -- Is_Static_Subtype --
3688 -----------------------
3690 -- Determines if Typ is a static subtype as defined in (RM 4.9(26))
3692 function Is_Static_Subtype (Typ : Entity_Id) return Boolean is
3693 Base_T : constant Entity_Id := Base_Type (Typ);
3694 Anc_Subt : Entity_Id;
3697 -- First a quick check on the non static subtype flag. As described
3698 -- in further detail in Einfo, this flag is not decisive in all cases,
3699 -- but if it is set, then the subtype is definitely non-static.
3701 if Is_Non_Static_Subtype (Typ) then
3705 Anc_Subt := Ancestor_Subtype (Typ);
3707 if Anc_Subt = Empty then
3711 if Is_Generic_Type (Root_Type (Base_T))
3712 or else Is_Generic_Actual_Type (Base_T)
3718 elsif Is_String_Type (Typ) then
3720 Ekind (Typ) = E_String_Literal_Subtype
3722 (Is_Static_Subtype (Component_Type (Typ))
3723 and then Is_Static_Subtype (Etype (First_Index (Typ))));
3727 elsif Is_Scalar_Type (Typ) then
3728 if Base_T = Typ then
3732 return Is_Static_Subtype (Anc_Subt)
3733 and then Is_Static_Expression (Type_Low_Bound (Typ))
3734 and then Is_Static_Expression (Type_High_Bound (Typ));
3737 -- Types other than string and scalar types are never static
3742 end Is_Static_Subtype;
3744 --------------------
3745 -- Not_Null_Range --
3746 --------------------
3748 function Not_Null_Range (Lo : Node_Id; Hi : Node_Id) return Boolean is
3749 Typ : constant Entity_Id := Etype (Lo);
3752 if not Compile_Time_Known_Value (Lo)
3753 or else not Compile_Time_Known_Value (Hi)
3758 if Is_Discrete_Type (Typ) then
3759 return Expr_Value (Lo) <= Expr_Value (Hi);
3762 pragma Assert (Is_Real_Type (Typ));
3764 return Expr_Value_R (Lo) <= Expr_Value_R (Hi);
3772 function OK_Bits (N : Node_Id; Bits : Uint) return Boolean is
3774 -- We allow a maximum of 500,000 bits which seems a reasonable limit
3776 if Bits < 500_000 then
3780 Error_Msg_N ("static value too large, capacity exceeded", N);
3789 procedure Out_Of_Range (N : Node_Id) is
3791 -- If we have the static expression case, then this is an illegality
3792 -- in Ada 95 mode, except that in an instance, we never generate an
3793 -- error (if the error is legitimate, it was already diagnosed in
3794 -- the template). The expression to compute the length of a packed
3795 -- array is attached to the array type itself, and deserves a separate
3798 if Is_Static_Expression (N)
3799 and then not In_Instance
3800 and then not In_Inlined_Body
3801 and then Ada_Version >= Ada_95
3803 if Nkind (Parent (N)) = N_Defining_Identifier
3804 and then Is_Array_Type (Parent (N))
3805 and then Present (Packed_Array_Type (Parent (N)))
3806 and then Present (First_Rep_Item (Parent (N)))
3809 ("length of packed array must not exceed Integer''Last",
3810 First_Rep_Item (Parent (N)));
3811 Rewrite (N, Make_Integer_Literal (Sloc (N), Uint_1));
3814 Apply_Compile_Time_Constraint_Error
3815 (N, "value not in range of}", CE_Range_Check_Failed);
3818 -- Here we generate a warning for the Ada 83 case, or when we are
3819 -- in an instance, or when we have a non-static expression case.
3822 Apply_Compile_Time_Constraint_Error
3823 (N, "value not in range of}?", CE_Range_Check_Failed);
3827 -------------------------
3828 -- Rewrite_In_Raise_CE --
3829 -------------------------
3831 procedure Rewrite_In_Raise_CE (N : Node_Id; Exp : Node_Id) is
3832 Typ : constant Entity_Id := Etype (N);
3835 -- If we want to raise CE in the condition of a raise_CE node
3836 -- we may as well get rid of the condition
3838 if Present (Parent (N))
3839 and then Nkind (Parent (N)) = N_Raise_Constraint_Error
3841 Set_Condition (Parent (N), Empty);
3843 -- If the expression raising CE is a N_Raise_CE node, we can use
3844 -- that one. We just preserve the type of the context
3846 elsif Nkind (Exp) = N_Raise_Constraint_Error then
3850 -- We have to build an explicit raise_ce node
3854 Make_Raise_Constraint_Error (Sloc (Exp),
3855 Reason => CE_Range_Check_Failed));
3856 Set_Raises_Constraint_Error (N);
3859 end Rewrite_In_Raise_CE;
3861 ---------------------
3862 -- String_Type_Len --
3863 ---------------------
3865 function String_Type_Len (Stype : Entity_Id) return Uint is
3866 NT : constant Entity_Id := Etype (First_Index (Stype));
3870 if Is_OK_Static_Subtype (NT) then
3873 T := Base_Type (NT);
3876 return Expr_Value (Type_High_Bound (T)) -
3877 Expr_Value (Type_Low_Bound (T)) + 1;
3878 end String_Type_Len;
3880 ------------------------------------
3881 -- Subtypes_Statically_Compatible --
3882 ------------------------------------
3884 function Subtypes_Statically_Compatible
3886 T2 : Entity_Id) return Boolean
3889 if Is_Scalar_Type (T1) then
3891 -- Definitely compatible if we match
3893 if Subtypes_Statically_Match (T1, T2) then
3896 -- If either subtype is nonstatic then they're not compatible
3898 elsif not Is_Static_Subtype (T1)
3899 or else not Is_Static_Subtype (T2)
3903 -- If either type has constraint error bounds, then consider that
3904 -- they match to avoid junk cascaded errors here.
3906 elsif not Is_OK_Static_Subtype (T1)
3907 or else not Is_OK_Static_Subtype (T2)
3911 -- Base types must match, but we don't check that (should
3912 -- we???) but we do at least check that both types are
3913 -- real, or both types are not real.
3915 elsif Is_Real_Type (T1) /= Is_Real_Type (T2) then
3918 -- Here we check the bounds
3922 LB1 : constant Node_Id := Type_Low_Bound (T1);
3923 HB1 : constant Node_Id := Type_High_Bound (T1);
3924 LB2 : constant Node_Id := Type_Low_Bound (T2);
3925 HB2 : constant Node_Id := Type_High_Bound (T2);
3928 if Is_Real_Type (T1) then
3930 (Expr_Value_R (LB1) > Expr_Value_R (HB1))
3932 (Expr_Value_R (LB2) <= Expr_Value_R (LB1)
3934 Expr_Value_R (HB1) <= Expr_Value_R (HB2));
3938 (Expr_Value (LB1) > Expr_Value (HB1))
3940 (Expr_Value (LB2) <= Expr_Value (LB1)
3942 Expr_Value (HB1) <= Expr_Value (HB2));
3947 elsif Is_Access_Type (T1) then
3948 return not Is_Constrained (T2)
3949 or else Subtypes_Statically_Match
3950 (Designated_Type (T1), Designated_Type (T2));
3953 return (Is_Composite_Type (T1) and then not Is_Constrained (T2))
3954 or else Subtypes_Statically_Match (T1, T2);
3956 end Subtypes_Statically_Compatible;
3958 -------------------------------
3959 -- Subtypes_Statically_Match --
3960 -------------------------------
3962 -- Subtypes statically match if they have statically matching constraints
3963 -- (RM 4.9.1(2)). Constraints statically match if there are none, or if
3964 -- they are the same identical constraint, or if they are static and the
3965 -- values match (RM 4.9.1(1)).
3967 function Subtypes_Statically_Match (T1, T2 : Entity_Id) return Boolean is
3969 -- A type always statically matches itself
3976 elsif Is_Scalar_Type (T1) then
3978 -- Base types must be the same
3980 if Base_Type (T1) /= Base_Type (T2) then
3984 -- A constrained numeric subtype never matches an unconstrained
3985 -- subtype, i.e. both types must be constrained or unconstrained.
3987 -- To understand the requirement for this test, see RM 4.9.1(1).
3988 -- As is made clear in RM 3.5.4(11), type Integer, for example
3989 -- is a constrained subtype with constraint bounds matching the
3990 -- bounds of its corresponding uncontrained base type. In this
3991 -- situation, Integer and Integer'Base do not statically match,
3992 -- even though they have the same bounds.
3994 -- We only apply this test to types in Standard and types that
3995 -- appear in user programs. That way, we do not have to be
3996 -- too careful about setting Is_Constrained right for itypes.
3998 if Is_Numeric_Type (T1)
3999 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4000 and then (Scope (T1) = Standard_Standard
4001 or else Comes_From_Source (T1))
4002 and then (Scope (T2) = Standard_Standard
4003 or else Comes_From_Source (T2))
4007 -- A generic scalar type does not statically match its base
4008 -- type (AI-311). In this case we make sure that the formals,
4009 -- which are first subtypes of their bases, are constrained.
4011 elsif Is_Generic_Type (T1)
4012 and then Is_Generic_Type (T2)
4013 and then (Is_Constrained (T1) /= Is_Constrained (T2))
4018 -- If there was an error in either range, then just assume
4019 -- the types statically match to avoid further junk errors
4021 if Error_Posted (Scalar_Range (T1))
4023 Error_Posted (Scalar_Range (T2))
4028 -- Otherwise both types have bound that can be compared
4031 LB1 : constant Node_Id := Type_Low_Bound (T1);
4032 HB1 : constant Node_Id := Type_High_Bound (T1);
4033 LB2 : constant Node_Id := Type_Low_Bound (T2);
4034 HB2 : constant Node_Id := Type_High_Bound (T2);
4037 -- If the bounds are the same tree node, then match
4039 if LB1 = LB2 and then HB1 = HB2 then
4042 -- Otherwise bounds must be static and identical value
4045 if not Is_Static_Subtype (T1)
4046 or else not Is_Static_Subtype (T2)
4050 -- If either type has constraint error bounds, then say
4051 -- that they match to avoid junk cascaded errors here.
4053 elsif not Is_OK_Static_Subtype (T1)
4054 or else not Is_OK_Static_Subtype (T2)
4058 elsif Is_Real_Type (T1) then
4060 (Expr_Value_R (LB1) = Expr_Value_R (LB2))
4062 (Expr_Value_R (HB1) = Expr_Value_R (HB2));
4066 Expr_Value (LB1) = Expr_Value (LB2)
4068 Expr_Value (HB1) = Expr_Value (HB2);
4073 -- Type with discriminants
4075 elsif Has_Discriminants (T1) or else Has_Discriminants (T2) then
4077 -- Because of view exchanges in multiple instantiations, conformance
4078 -- checking might try to match a partial view of a type with no
4079 -- discriminants with a full view that has defaulted discriminants.
4080 -- In such a case, use the discriminant constraint of the full view,
4081 -- which must exist because we know that the two subtypes have the
4084 if Has_Discriminants (T1) /= Has_Discriminants (T2) then
4086 if Is_Private_Type (T2)
4087 and then Present (Full_View (T2))
4088 and then Has_Discriminants (Full_View (T2))
4090 return Subtypes_Statically_Match (T1, Full_View (T2));
4092 elsif Is_Private_Type (T1)
4093 and then Present (Full_View (T1))
4094 and then Has_Discriminants (Full_View (T1))
4096 return Subtypes_Statically_Match (Full_View (T1), T2);
4107 DL1 : constant Elist_Id := Discriminant_Constraint (T1);
4108 DL2 : constant Elist_Id := Discriminant_Constraint (T2);
4116 elsif Is_Constrained (T1) /= Is_Constrained (T2) then
4120 -- Now loop through the discriminant constraints
4122 -- Note: the guard here seems necessary, since it is possible at
4123 -- least for DL1 to be No_Elist. Not clear this is reasonable ???
4125 if Present (DL1) and then Present (DL2) then
4126 DA1 := First_Elmt (DL1);
4127 DA2 := First_Elmt (DL2);
4128 while Present (DA1) loop
4130 Expr1 : constant Node_Id := Node (DA1);
4131 Expr2 : constant Node_Id := Node (DA2);
4134 if not Is_Static_Expression (Expr1)
4135 or else not Is_Static_Expression (Expr2)
4139 -- If either expression raised a constraint error,
4140 -- consider the expressions as matching, since this
4141 -- helps to prevent cascading errors.
4143 elsif Raises_Constraint_Error (Expr1)
4144 or else Raises_Constraint_Error (Expr2)
4148 elsif Expr_Value (Expr1) /= Expr_Value (Expr2) then
4161 -- A definite type does not match an indefinite or classwide type
4162 -- However, a generic type with unknown discriminants may be
4163 -- instantiated with a type with no discriminants, and conformance
4164 -- checking on an inherited operation may compare the actual with
4165 -- the subtype that renames it in the instance.
4168 Has_Unknown_Discriminants (T1) /= Has_Unknown_Discriminants (T2)
4171 Is_Generic_Actual_Type (T1) or else Is_Generic_Actual_Type (T2);
4175 elsif Is_Array_Type (T1) then
4177 -- If either subtype is unconstrained then both must be,
4178 -- and if both are unconstrained then no further checking
4181 if not Is_Constrained (T1) or else not Is_Constrained (T2) then
4182 return not (Is_Constrained (T1) or else Is_Constrained (T2));
4185 -- Both subtypes are constrained, so check that the index
4186 -- subtypes statically match.
4189 Index1 : Node_Id := First_Index (T1);
4190 Index2 : Node_Id := First_Index (T2);
4193 while Present (Index1) loop
4195 Subtypes_Statically_Match (Etype (Index1), Etype (Index2))
4200 Next_Index (Index1);
4201 Next_Index (Index2);
4207 elsif Is_Access_Type (T1) then
4208 if Can_Never_Be_Null (T1) /= Can_Never_Be_Null (T2) then
4211 elsif Ekind (T1) = E_Access_Subprogram_Type
4212 or else Ekind (T1) = E_Anonymous_Access_Subprogram_Type
4216 (Designated_Type (T1),
4217 Designated_Type (T2));
4220 Subtypes_Statically_Match
4221 (Designated_Type (T1),
4222 Designated_Type (T2))
4223 and then Is_Access_Constant (T1) = Is_Access_Constant (T2);
4226 -- All other types definitely match
4231 end Subtypes_Statically_Match;
4237 function Test (Cond : Boolean) return Uint is
4246 ---------------------------------
4247 -- Test_Expression_Is_Foldable --
4248 ---------------------------------
4252 procedure Test_Expression_Is_Foldable
4262 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4266 -- If operand is Any_Type, just propagate to result and do not
4267 -- try to fold, this prevents cascaded errors.
4269 if Etype (Op1) = Any_Type then
4270 Set_Etype (N, Any_Type);
4273 -- If operand raises constraint error, then replace node N with the
4274 -- raise constraint error node, and we are obviously not foldable.
4275 -- Note that this replacement inherits the Is_Static_Expression flag
4276 -- from the operand.
4278 elsif Raises_Constraint_Error (Op1) then
4279 Rewrite_In_Raise_CE (N, Op1);
4282 -- If the operand is not static, then the result is not static, and
4283 -- all we have to do is to check the operand since it is now known
4284 -- to appear in a non-static context.
4286 elsif not Is_Static_Expression (Op1) then
4287 Check_Non_Static_Context (Op1);
4288 Fold := Compile_Time_Known_Value (Op1);
4291 -- An expression of a formal modular type is not foldable because
4292 -- the modulus is unknown.
4294 elsif Is_Modular_Integer_Type (Etype (Op1))
4295 and then Is_Generic_Type (Etype (Op1))
4297 Check_Non_Static_Context (Op1);
4300 -- Here we have the case of an operand whose type is OK, which is
4301 -- static, and which does not raise constraint error, we can fold.
4304 Set_Is_Static_Expression (N);
4308 end Test_Expression_Is_Foldable;
4312 procedure Test_Expression_Is_Foldable
4319 Rstat : constant Boolean := Is_Static_Expression (Op1)
4320 and then Is_Static_Expression (Op2);
4326 if Debug_Flag_Dot_F and then In_Extended_Main_Source_Unit (N) then
4330 -- If either operand is Any_Type, just propagate to result and
4331 -- do not try to fold, this prevents cascaded errors.
4333 if Etype (Op1) = Any_Type or else Etype (Op2) = Any_Type then
4334 Set_Etype (N, Any_Type);
4337 -- If left operand raises constraint error, then replace node N with
4338 -- the raise constraint error node, and we are obviously not foldable.
4339 -- Is_Static_Expression is set from the two operands in the normal way,
4340 -- and we check the right operand if it is in a non-static context.
4342 elsif Raises_Constraint_Error (Op1) then
4344 Check_Non_Static_Context (Op2);
4347 Rewrite_In_Raise_CE (N, Op1);
4348 Set_Is_Static_Expression (N, Rstat);
4351 -- Similar processing for the case of the right operand. Note that
4352 -- we don't use this routine for the short-circuit case, so we do
4353 -- not have to worry about that special case here.
4355 elsif Raises_Constraint_Error (Op2) then
4357 Check_Non_Static_Context (Op1);
4360 Rewrite_In_Raise_CE (N, Op2);
4361 Set_Is_Static_Expression (N, Rstat);
4364 -- Exclude expressions of a generic modular type, as above
4366 elsif Is_Modular_Integer_Type (Etype (Op1))
4367 and then Is_Generic_Type (Etype (Op1))
4369 Check_Non_Static_Context (Op1);
4372 -- If result is not static, then check non-static contexts on operands
4373 -- since one of them may be static and the other one may not be static
4375 elsif not Rstat then
4376 Check_Non_Static_Context (Op1);
4377 Check_Non_Static_Context (Op2);
4378 Fold := Compile_Time_Known_Value (Op1)
4379 and then Compile_Time_Known_Value (Op2);
4382 -- Else result is static and foldable. Both operands are static,
4383 -- and neither raises constraint error, so we can definitely fold.
4386 Set_Is_Static_Expression (N);
4391 end Test_Expression_Is_Foldable;
4397 procedure To_Bits (U : Uint; B : out Bits) is
4399 for J in 0 .. B'Last loop
4400 B (J) := (U / (2 ** J)) mod 2 /= 0;
4404 --------------------
4405 -- Why_Not_Static --
4406 --------------------
4408 procedure Why_Not_Static (Expr : Node_Id) is
4409 N : constant Node_Id := Original_Node (Expr);
4413 procedure Why_Not_Static_List (L : List_Id);
4414 -- A version that can be called on a list of expressions. Finds
4415 -- all non-static violations in any element of the list.
4417 -------------------------
4418 -- Why_Not_Static_List --
4419 -------------------------
4421 procedure Why_Not_Static_List (L : List_Id) is
4425 if Is_Non_Empty_List (L) then
4427 while Present (N) loop
4432 end Why_Not_Static_List;
4434 -- Start of processing for Why_Not_Static
4437 -- If in ACATS mode (debug flag 2), then suppress all these
4438 -- messages, this avoids massive updates to the ACATS base line.
4440 if Debug_Flag_2 then
4444 -- Ignore call on error or empty node
4446 if No (Expr) or else Nkind (Expr) = N_Error then
4450 -- Preprocessing for sub expressions
4452 if Nkind (Expr) in N_Subexpr then
4454 -- Nothing to do if expression is static
4456 if Is_OK_Static_Expression (Expr) then
4460 -- Test for constraint error raised
4462 if Raises_Constraint_Error (Expr) then
4464 ("expression raises exception, cannot be static " &
4465 "(RM 4.9(34))!", N);
4469 -- If no type, then something is pretty wrong, so ignore
4471 Typ := Etype (Expr);
4477 -- Type must be scalar or string type
4479 if not Is_Scalar_Type (Typ)
4480 and then not Is_String_Type (Typ)
4483 ("static expression must have scalar or string type " &
4489 -- If we got through those checks, test particular node kind
4492 when N_Expanded_Name | N_Identifier | N_Operator_Symbol =>
4495 if Is_Named_Number (E) then
4498 elsif Ekind (E) = E_Constant then
4499 if not Is_Static_Expression (Constant_Value (E)) then
4501 ("& is not a static constant (RM 4.9(5))!", N, E);
4506 ("& is not static constant or named number " &
4507 "(RM 4.9(5))!", N, E);
4510 when N_Binary_Op | N_And_Then | N_Or_Else | N_Membership_Test =>
4511 if Nkind (N) in N_Op_Shift then
4513 ("shift functions are never static (RM 4.9(6,18))!", N);
4516 Why_Not_Static (Left_Opnd (N));
4517 Why_Not_Static (Right_Opnd (N));
4521 Why_Not_Static (Right_Opnd (N));
4523 when N_Attribute_Reference =>
4524 Why_Not_Static_List (Expressions (N));
4526 E := Etype (Prefix (N));
4528 if E = Standard_Void_Type then
4532 -- Special case non-scalar'Size since this is a common error
4534 if Attribute_Name (N) = Name_Size then
4536 ("size attribute is only static for scalar type " &
4537 "(RM 4.9(7,8))", N);
4541 elsif Is_Array_Type (E) then
4542 if Attribute_Name (N) /= Name_First
4544 Attribute_Name (N) /= Name_Last
4546 Attribute_Name (N) /= Name_Length
4549 ("static array attribute must be Length, First, or Last " &
4552 -- Since we know the expression is not-static (we already
4553 -- tested for this, must mean array is not static).
4557 ("prefix is non-static array (RM 4.9(8))!", Prefix (N));
4562 -- Special case generic types, since again this is a common
4563 -- source of confusion.
4565 elsif Is_Generic_Actual_Type (E)
4570 ("attribute of generic type is never static " &
4571 "(RM 4.9(7,8))!", N);
4573 elsif Is_Static_Subtype (E) then
4576 elsif Is_Scalar_Type (E) then
4578 ("prefix type for attribute is not static scalar subtype " &
4583 ("static attribute must apply to array/scalar type " &
4584 "(RM 4.9(7,8))!", N);
4587 when N_String_Literal =>
4589 ("subtype of string literal is non-static (RM 4.9(4))!", N);
4591 when N_Explicit_Dereference =>
4593 ("explicit dereference is never static (RM 4.9)!", N);
4595 when N_Function_Call =>
4596 Why_Not_Static_List (Parameter_Associations (N));
4597 Error_Msg_N ("non-static function call (RM 4.9(6,18))!", N);
4599 when N_Parameter_Association =>
4600 Why_Not_Static (Explicit_Actual_Parameter (N));
4602 when N_Indexed_Component =>
4604 ("indexed component is never static (RM 4.9)!", N);
4606 when N_Procedure_Call_Statement =>
4608 ("procedure call is never static (RM 4.9)!", N);
4610 when N_Qualified_Expression =>
4611 Why_Not_Static (Expression (N));
4613 when N_Aggregate | N_Extension_Aggregate =>
4615 ("an aggregate is never static (RM 4.9)!", N);
4618 Why_Not_Static (Low_Bound (N));
4619 Why_Not_Static (High_Bound (N));
4621 when N_Range_Constraint =>
4622 Why_Not_Static (Range_Expression (N));
4624 when N_Subtype_Indication =>
4625 Why_Not_Static (Constraint (N));
4627 when N_Selected_Component =>
4629 ("selected component is never static (RM 4.9)!", N);
4633 ("slice is never static (RM 4.9)!", N);
4635 when N_Type_Conversion =>
4636 Why_Not_Static (Expression (N));
4638 if not Is_Scalar_Type (Etype (Prefix (N)))
4639 or else not Is_Static_Subtype (Etype (Prefix (N)))
4642 ("static conversion requires static scalar subtype result " &
4646 when N_Unchecked_Type_Conversion =>
4648 ("unchecked type conversion is never static (RM 4.9)!", N);